Basically you want to start with Mighty No. 5, the Military Weapon based Robot...

No. 5 has one of the easier stages to navigate and his pattern is fairly easy to figure out. He was also one of the first stages released in the demo version of the game so it should all seem really familiar.

After you're done with him, work your way around the circle.

Boss Order for less visual learners:

1. Mighty No. 5 (Battalion)
   
2. Mighty No. 4 (Seismic)
   
3. Mighty No. 7 (Brandish)
   
4. Mighty No. 3 (Dynatron)
   
5. Mighty No. 8 (Countershade)
   
6. Mighty No. 6 (Aviator)
   
7. Mighty No. 1 (Pyrogen)
   
8. Mighty No. 2 (Cryosphere)

Most of the boss weapons in this game are abysmal to use, require way too much energy and take some practice to get used to. Don't expect to kill a boss by just spamming their weakness on them.
Most of the time there's a very finite window of opportunity you get to use the weapon to it's full potential on them. Otherwise you'll just be sitting there waiting for that moment to happen and trying not to get instant killed or take too much damage. It takes timing and practice just like the crappy dash mechanics in this game.


Mighty No. 5 (Ballistic)

Allows you to trigger switches from far away by planting a bomb on them then setting them off while you stand in front the door / laser trap it triggers. It's a must use weapon for later stages. Hotkey it!

Mighty No. 6 (Aviator)

Allows you to basically increase your jump height by almost triple and allows Beck to float down slowly. This is a required ability in the final two stages of the game where Keji decided it was a good idea to have a giant 10 screen wide pitfall with wind tunnels shooting up in random spots to elevate your height as you use this stupid ability / dash to get across it.

There's also numerous sections in the robot factory stage that are impossible to navigate without using this item. You can't beat the game without using this item at some point. Hotkey it!

Mighty No. 7 (Brandish)

This is basically "Zero" mode for those of you familiar with Mega Man X. Beck even looks like him with the yellow scarf / hair pony tail thing. This weapon has very high utility and you can almost beat 70% of the game while in this form. The basic sword slice does not use up any energy, it cuts through enemy and boss defenses (Including one of the final bosses phases where you shouldn't be able to damage it) Highest DPS weapon in the game, even more than spamming Beck's Arm Cannon. Only downside is you have to be in close proximity. Hotkey it for utility purposes!


Mighty No. 8 (Countershade)

There's a spot in the Robot Factory that requires you to shoot this weapon through a small opening and ricochet it off of a wall to trigger a switch. It's the only spot in the game I had to use this weapon.

It's almost impossible to beat Aviator without using Countershades sniper rifle. One of the most obnoxious boss fights in the entire game, so make sure you have it and use it on the small flying robot to ricochet the bullets and hit Aviator with it.


Only use the following weapons on their respective bosses, they have no other real practical use in the game:

Mighty No. 1 (Pyrogen)
Mighty No. 2 (Cryosphere)
Mighty No. 4 (Seismic)


Mighty No. 3 (Dynatron)

Her weapon is complete and utter garbage. I never found a practical use for it even though it's supposed to be Countershades weakness. The energy depletes too quickly and the DPS on it is abysmal as hell. Total garbage. Which is almost a travesty considering Elec Man's weapon in Mega Man was the most OP ♥♥♥♥ ever...