Escape Artists are the best frontliners because of their default 'Stubborn' (immune to Stun and hostile Move) and Chain Wall (damage reduction for all characters behind). Escape Artist with Chain Wall is a must for all boss fights. Her one weakness are the turban cops with their stancebreaker skill. In this case, the Double Clown Defense is the better strategy.

Optimal Skills: Chain Wall is all that really matters. Handcuffs and Lockthrow have their uses.
Optimal Passives: Devotion/Health self heal; Stun/Move resist is useless due to class passive
Preferred Slot: 1
Class Passive: Stubborn (immune to Move and Stun)

Recommended Gadgets: Sand Glass – the sooner the Escape Artist can activate the stance, the less damage the party takes. Vambraces to increase Defense, Mini Terrarium to increase received heals, or Heart Pendant to increase health are useful as well since she'll take most of the damage.

Legends: Freja in District 3 & Gunda in District 6
They only have their one unique skill (not two passives) 'Second Chance' – one-time 10 % to evade a lethal blow. This ability is just bad, and the fact that it replaces Stubborn makes it even worse. Gunda is a universal and has Chain Wall, Freja is orange/main event and does not. The only reason to replace Yvonne is her lack of show synergies, but it's a weak reason. If a character is 90 % in combat, circus show stats and synergies don't matter. Just buy a second Escape Artist who is exactly the same as her from the train early on, and you're set for the frontline. Any random with universal slot and Chain Wall is better than the legends because of Stubborn, and also has a chance to have a second useful passive.

Strongmen are immune to hostile Move in slots 1 and 2, but Balthazar has a more useful skill with 'Brutal Spot' when he's in slot 3 or 4. 'Weight Throw' and 'Boomerang' are the important skills for him. Strongmen also work well in slot 2 with 'Spinebreaker', 'Stunning Attack' and 'Ground Shatter' as the main skills. Strongman behind Escape Artist makes 50 % of the party immune to shuffles which is very useful in the final boss fight.

Optimal Skills (for Slot 2): Spinebreaker, Ground Shatter, Stunning Attack
Optimal Skills (for Slot 3): Boomerang, Weight Throw, Ground Shatter
Optimal Passives (for slot 2): Jolly Opening/Resolution, Ardent/Faithful Spot
Optimal Passives (for slot 3): Steady Spot/Faithful Spot/Ardent Spot, Jolly Opening/Resolution
Preferred Slot: 2 or 3, depending on passives and skills
Class Passive: Immovable (immune to Move when in slots 1 and 2)
Recommended Gadgets: Watch - Strongman desperately needs Precision, Mannequin to lower cost of Ground Shatter

Legends: Cuthbert in District 3, Bender in District 4
Both have Immovable + the unique passive 'Strongest' (25 % damage increase). Cuthbert is available early, and he's a universal. Bender is green/afterpiece and lacks Ground Shatter. Cuthbert is a good replacement for Balthazar (or addition if you keep Balthazar for slot 3).

Clowns are the allrounders you want to bring to any fight. They are healers, boosters (especially early on, Trumpet Boost helps with the Strongman's atrocious Precision), off tanks, taunters; can lower enemy Devotion and break stances. Therefore, finding an optimal Clown early on goes a very long way.

Double Clown Defense: Clowns in the 2 front slots; each with Taunt & Clown Care (and ideally Vambraces and/or Mini Terrarium gadgets). Slot 1 taunts, Slot 2 heals him; switch whenever Slot 2's Devotion gets too low or Slot 1 is too damaged. This is the best counter to hostile stancebreaker skills (turban cops).

Optimal Skills: Ball Throw, Clown Care, Taunt, Mock Throw
Optimal Passives: Jolly Opening (to lower the cost of Clown Care)
Preferred Slot: 2 or 3 (in Smog, Clown can be in 4/backline to function as buffer/healer only)
Class Passive: Cheerful (heals random ally every round)
Recommended Gadgets: Mannequin - lowers Devotion cost of Clown Care, Watch - Precision for Ball/Mock Throw

Legends: Septimus in District 4, Percival in District 6
Both have 'Challenger' instead of 'Cheerful'; no second passive. 'Challenger' has a 60 % chance to taunt all enemies if the Clown is in slot 1. Useful for the Double Clown Defense strategy. Percival is pink/support act, Septimus is universal. Both have Ball Throw and Clown Care, neither has Mock Throw.

Fire Blowers are glass cannons. They are a must have for Night fights, but also useful in Smog and Crowd fights. The uniques of this class are significantly better than the best randoms due to their 'Walk With Me' skill (all attacks ignite/do DoT). The first unique, Nevaeh, is available in District 4. She's a pink/supporting act which is the only and negligable downside. 'Fire Throw' is a stronger version of the Clown's Ball Throw (fire/devotion dmg instead of water/devotion, trades move chance for precision), so this is the most crucial skill for Fire Blowers.

Optimal Skills: Fire Whirl, Fire Throw, Fire Ring, Fire Blow
Optimal Passives: Walk With Me (uniques only), anything that activates in slots 3 and 4
Preferred Slot: 4 (in Smog fights, move to 3)
Class Passive: Hot Blooded (immune to Fire damage)
Recommended Gadgets: Sonic Screwdriver (to turn Fire Blow into an AoE stancebreaker), Pen - increased DoT (espcially effective on the uniques), Lucky Coin - increased crit change

Legends: Nevaeh in District 4, Angel in District 6
Both have 'Walk With Me' as passive; Nevaeh also has 'Hot Blooded'. 'Walk With Me' is one of the best passives. All attacks deal Fire damage over time, meaning Fire Blow (which both have) ignites all enemies at once. Nevaeh is pink/support act, Angel is blue/opener. Nevaeh is available much earlier and has both passives, so she's by far the better choice.

Illusionists are the DPS carry in nearly every situation. They have a fair amount of utility skills along with the best AoE in the game. Horace, the first unique to become available (District 3), has the ideal mix of skills. The ideal illusionist is one that has the same skills and is universal (Horace is orange/main event). Eugene, the illusionist you automatically get after the District 1 boss fight, lacks the most important skill 'The Apparition' and should therefore be replaced immediately. Around level 3 – 4, the Illusionist starts hitting like a truck with The Apparition and somewhat reliably brings in double/triple strikes (which increase Devotion for all allies).

Optimal Skills: The Apparition, The Saw, That's my Card, Glitter
Optimal Passives: Jolly Resolution, Jolly Opening, anything that activates in slots 3 and 4
Preferred Slot: 4 (in Smog fights, move to 3)
Class Passive: Repel (when in slot 4, 50 % of all incoming damage gets redirected to slot 3)
Recommended Gadgets: Sonic Screwdriver (to turn The Apparition into an AoE stancebreaker), Lucky Coin - increased crit chance, Telescope – chance to ignore Defense

Legends: Horace in District 3, Ebenezer in District 4
Horace is orange/main event and has 'Repel' and the unique 'Now You See Me' (50 % to summon 3 clones when he's the last man standing); Ebenezer blue/opener and only has the latter. Ebenezer also lacks The Apparition, so what is even the point. Horace, on the other hand, can kill all bosses on hard and with little damage from other sources. This has nothing to do with the unique, and everything with 'Repel' and his skills. Any random Illusionist with the same skills can do it. Likely even better with a more useful second passive. Horace is the earliest available Legend though, so he's worth it for circus stats. Early drafts have a main event Illusionist slot anyway, so if you need to park him for a few battles, he's at least not a hinderance.

Snake Charmers are the best Devotion healers with 'Belly Dance'. It permanently increases Devotion for all allies. The other important skills are 'Fear' (Devotion attack) and 'Rattle On' (Precision debuff). They are invaluable in Smog battles and effective in Night battles, but can be brought into any fight to restore Devotion. Since Snake Charmers are mostly a support class, they are also prime targets for utility gadgets like Lunch Box (lower food cost) to conserve resources.

Optimal Skills: Belly Dance, Fear, Rattle On
Optimal Passives: Jolly Resolution, Jolly Opening, anything that activates in slots 3 and 4
Preferred Slot: 4
Class Passive: Snake Guardian (immune to poison when standing in slot 2 or 3)
Recommended Gadgets: Lunch Box, Mannequin if you have a spare one

Legends: Raja and Nida, both in District 4
Raja is pink/support, Nida is blue/opener. Both have 'Venom' instead of 'Snake Guardian' – each skill effect has +1 round duration. Raja is pointless since she doesn't have 'Belly Dance', the best Devotion heal, and lacks 'Fear', one of the strongest Devotion attacks, too. Nida has both. The unique passive is a lot better than the regular skill, but neither is all that useful. A random Snake Charmer with universal slot and the right skills is better in most situations.

A class I usually dismiss right away or only use for their performance stats. To me, it's all neither here nor there. 'Sword Swallow' is the best stun in the game, but that's the only thing Fakir really has going for him. Not worth the maintenance cost in my opinion.

Optimal Skills: Sword Swallow
Optimal Passives: not a clue
Preferred Slot: probably 3
Class Passive: Agony (taking damage increases devotion)
Recommended Gadgets: Lunch Box, so he's at least free at first

Legends: Dipankar and Yordy, both in District 5
They have 'Frenzy' instead of 'Agony' (no second passive) which increases the damage the lower their health drops. Marginally more useful than 'Agony'. Yordy is pink/support, Dipankar is universal. Both have Sword Swallow and decent synergies. Dipankar is the better choice due to his universal slot.

A weird class. More style than substance. The character design is amazing, but they are not as useful as I wish they were. The uniques are much better than the randoms due to their unique skill, so it is worth waiting for them. Both uniques are located in District 4. Ventriloquists are relatively strong in Smog fights with Poison and/or Devotion damage which is inconvenient because their strong skills come at a high Devotion cost. The AoE, 'Evil Laugh', permanently lowers the Devotion of all allies. Not worth it.

Optimal Skills: Hit yourself
Optimal Passives: Jolly Opening/Resolution, Faithful Spot (slots 2 and 3)
Preferred Slot: 2 or 3
Class Passive: Reckless (immune to Hypnotise, Stun, Taunt)
Recommended Gadgets: Mannequin to reduce Devotion cost

Legends: Clayton and Hakeem, both in District 4
Both have 'Mass Influence' in addition to 'Reckless' – the former halves the strengths of all whispers, but makes them AoE. This also applies to 'Feel Invincible' (ally Devotion boost). Clayton is orange/main event, Hakeem is blue/opener. The main difference – and reason I prefer Hakeem – is that Clayton has 'Evil Laugh' and Hakeem has 'Hit Yourself'. Both can be fun on Easy, but I don't recommend Ventriloquists in general for Normal/Hard.

Squishy, but the most effective damage dealer in Rain fights with the Electric Ring trap (Electric/Devotion damage), Poison and Water attacks. Placing traps and moving enemies through them with Clown's Ball Throw works very well. Trapeze Kick can be turned into a a decent stancebreaker with Sonic Screwdriver.

Optimal Skills: Electric Ring, Hula Blast, Trapeze Kick
Optimal Passives: Vigurous Spot, anything that activates on slots 3 and 4
Preferred Slot: 3 or 4
Class Passive: Footlight (gains 15 % temporary Devotion in slots 1 and 2)
Recommended Gadgets: Pen to increase DoT damage, Sonic Screwdriver for stancebreaking, Telescope to make Trapeze Kick ignore Defense

Legends: Ming and Guanyu, both in District 5
Both have 'Sidestep' instead of 'Footlight'; 33 % dodge chance. I find it more useful because I mostly play Acrobats in slots 3/4 for the Electric Ring. Guanyu is orange/main event, Ming is pink/support. Only the latter has Electric Ring. Guanyu can probably be fairly effective in slot 2, but I haven't tried it myself.

High damage and precision, but squishy and not as versatile as Illusionist. I rarely find use for this class. The uniques have 'Double Tap' which makes them throw twice the blades; the randoms have 'Under Pressure' which increases Precision by having negative effects. To me, the class looks useful on paper, but it just doesn't translate to my playstyle. Take these recommendations with a grain of salt.

Optimal Skills: Double Shot, Bullseye
Optimal Passives: Jolly Opening/Resolution, Faithful Spot (slots 3 and 4)
Preferred Slot: 3 or 4
Class Passive: Under Pressure (negative effects increase Precision)
Recommended Gadgets: Lucky Coin (increased crit change), Mannequin (lowers Devotion cost)

Legends: Aylen in District 4, Cindy in District 6
Both have 'Double Tap' in addition to 'Under Pressure'. Aylen is blue/opener, Cindy is green/afterpiece.

The most mobile class. Useful for an Iratus style strategy with 'Dive' (moving enemies into/through several traps). Decent stun, high Initiative, stancebreaking attack. It's less useful than Clown's Mock Throw despite the higher chance to break the stance since it can only target slots 3 and 4 and has to charge. Note that it targets the enemy, not the slot. If the enemy moves, Windmill Punch will still hit the targeted enemy, not whoever is in the targeted slot.

Optimal Skills: Dive, K.O., Windmill Punch if you have nothing better for stancebreaking
Optimal Passives: any that are not slot-activated since Stilt Boxer moves around a lot
Preferred Slot: 3 and 4 (due to their class skill 'Super Spring'; increased Crit Change in these slots)
Class Passive: Super Spring (15 % crit chance increase when in slots 3 or 4)
Recommended Gadgets: Lucky Coin - increased Crit Chance

Legends: Narantuyaa and Soyolmaa, both in District 6
Both have 'Heavy Mover' in addition to 'Super Spring' – all attacks move targets away. Very useful to punch enemies through a trap conga line. Narantuyaa is orange/main event, Soyalmaa is pink/support. Both are worthwhile.

The only class other than Snake Charmer to have a permanent Devotion increase for all allies with 'Parade'. Does Fire damage, so she's good in Night fights. 'Water Cannon' is useful to remove positive effects from all enemies.

Optimal Skills: Human Cannonball, Water Cannon, Parade
Optimal Passives: anything that activates on slot 2
Preferred Slot: 2
Class Passive: Hero's Stance (all received damage halved while in a stance)
Recommended Gadgets: any debuff/damage prevention

Legends: Getrude and Rose, both in District 6
Both have 'Bombardment' instead of 'Hero's Stance'; a 20 % damage increase. Rose is blue/opener, Gertrude is green/afterpiece. I haven't played them enough to tell if the unique passive makes them better Night damage dealers than Nevaeh. Gertude is probably the better choice either way because she has 'Water Cannon', and hostile Taunts are annoying with the ticking Bobbery meter.

Strong in Rain fights with mostly electric attacks. A solid slot 3 replacement for Strongman/Boomerang (switching water for electric damage). The 3 Pin Throw which jumps to the next enemy if it kills the initial target is useful to set up double kills. No Damage Reduction, but higher Initiative and Dodge than Strongman. No AoE, but more versatile since 'Pin Throw' can also hit the frontline. Ultimately a matter of taste.

Optimal Skills: 3 Pin Throw, Dazzling Flash
Optimal Passives: anythings that activates on slot 3
Preferred slot: 3
Class Passive: Inspiration (15 % damage increase as long as she has any kind of buff)

Legends: Edith and Charity, both in District 6
Charity has 'Disorient' instead of 'Inspiration'; 100 % chance to break stances. Edith has both passives. Charity is universal, Edith is green/afterpiece.

Their passive, 'Thick Skin', makes the Robot Bear (in slot 1) absorb 20 % of all damage dealt to the allies behind. Robot Bears have high health, but will still need to heal/get healed sometimes. Their skill 'Hibernate' can do that, but requires to move the Robot Bear to slots 3 or 4. It is therefore better not to let health drop too low in the first place.

Optimal Skills: Claws, Bite, Roar, Charge (since Robot Bear has no natural Move protection and might have to attack from the backline)
Optimal Passives: any protections for slot 1 (Stubborn Spot, Vigorous Spot, Solid Spot)
Preferred Slot: 1
Class Passive: Thick Skin (absorbs 20 % of all damage to allies when in slot 1)
Recommended Gadgets: Heart Pendant, Mini Terrarium, Gramophone

Legends: Kitt and Wally, both in District 6
Both have 'Bear Necessities' instead of 'Thick Skin'; 15 % self heal every turn. Kitt is pink/support, Wally is orange/main event and has the better skills (namely, 'Roar' to taunt). Not all that impressive on Hard; damage prevention is generally better than healing a ton.

Absurdly powerful. This class is a very late game unlock for a reason (unfortunately, only for you – as enemies, they show up in District 4). AoE stun, trap immunity, several 2-slot attacks, flexible positioning, low Devotion costs. For instance, the AoE stun hits all enemies and costs no devotion. It can be spammed every round, twice if you have Balancers in slots 1 and 2, with no drawbacks. The ability that does cost 5% Devotion hits randomly – three times, and has a 95 % chance to ignore Defense (on level 10).

Optimal Skills: Sonic Boom, Spin Kick; Raining Arrows
Optimal Passives: Jolly Opening/Resolution, Faithful Spot, Persistent Spot
Preferred Slot: 2 for stun, 3 for ranged damage
Class Passive: Watch Your Steps (trap immunity)
Recommened Gadgets: Mannequin if backliner (Raining Arrows costs Devotion and can only be used from slots 3 and 4), Lucky Coin, Watch, Hat

Legends: Pascal and Ferdinand, both in District 6
Both have 'Dance Battle' – 20 % dodge chance increase – in addition to 'Watch Your Steps'. Ferdinand is universal and does not have 'Raining Arrows', Pascal is orange/main event and does have it. Both have the stun, 'Sonic Boom'.