This is a basic guide on how to stomp through the levels of Hell with Lubu

Key points:
Lubu can generate insane amounts of musou recharge from shock

Lubu's XXY has wide sweeping attacks and that charge finisher can inflict shock
Lubu's XXXXXY has a large multi hit but with low area

Those are the basics of wiping things off the map

Here's the basic strategy (I have not beat Lvl 5 yet, will get there today, been dinking around on my steam deck and i have trouble playing things well on deck due to vision issues)

Prioritize shock, fist, and combo upgrades, the rest can be great, but since musou charges with shock, we are looking to have near unlimited musou
Approach every fight with XY to the biggest group of telegraphed attack (XXXY) has a much larger area, choose as needed.
Once you arent in fear of telegraphed attacks sweep with XXY as often as possible (this is assuming you have some chock token built up after a few levels
For the first first boss, you should always grab any character you can to complete you formation, this enables the big ultimate attack

Keep this habit going, sweeping XXY to inflict shock to recharge your musou, when done properly, you will fully, or almost fully recharge your musou with a single combo in a a large group

Prioritize your musou attack against "officers" the ones with health bars. Ive found that they have a tendency to drop the crystal balls that give an extra token.
Prioritize your token choices to shock, fist and the double wave tokens.

Once you have shock 3 you dont need those tokens as much.

Its also worth noting that pushing for the other attack tokens will enable attack action 3, which is a grab that will cause explosive shock attacks and add a large amount of musou charge

If you can use a formation that gives the 5% attack bonus for shock tokens, do so. Dont let Enma autoform you away from this formation. You power wont be as high, but your attack with it is insane.

For bosses your not looking to one phase kill. In fact you benefit from letting them recover from their first stagger. If you can use formation ultimate attack to kill in 1 phase, great, but its so easy to wipe then after the first stagger.

Use the fact that they summon after the first stagger to build your musou. Use XXY to build your musou if you used it on first stagger.

After that use musou to stagger again and use the formation attack. Build your musou with the mobs and then use the ultimate and musou to kill them on the second stagger.

If you have enough cumulative levels this will clear every boss depending on your skill level.

Getting his ultimate weapon is really helpful of course, so put this on you list when you can. I was able to clear several difficulty levels one after another using this pattern.

Short unformatted guide, but i hope it help. I know you have to farm a lot, and as others have said, avoid buying more formations as you move to unlock him. I used one of the other super character to farm till i could get him and the focused on progress. Until that point i only looked at Karma farming. You can clear 2500 karma on the first floor before the first boss if you get luck and play smart. Then leave and restart, only takes a few minutes to get 50k karma