Monokuma's Test floor 70 boss is way too hard

[That one guy]

There is nothing that my FULL U-TEAM can do to kill this piece of ♥♥♥♥ boss, I get a lot of good hits and the ♥♥♥♥ spams sleep, and just kills everyone with normal attacks. By the way I have tried putting anything on my team to increase their fortitude and the highest is about 350 and still they get inflicted with sleep. HOW THE ♥♥♥♥ DO YOU BEAT THIS LITTLE ♥♥♥♥! If anyone knows please for the love of god hold my hand and help me because this is becoming annyoing

[Chai]

I followed this guide, which according to it, here is some info about the boss:
Hitpoints: 10000
Skills: Wind Jet All, Sleep All
Resistance: Physical Damage, Status
Weakness: Wind barrier, cure status ailments, high fortitude to resist sleep, elemental damage

This guide helps with which characters do best in which stats. I finished this up a year ago so my brain is fried and I completely forget a lot of stuff, but basically looking at other people's builds helped me a lot. Unfortunately it's a little sweaty, and also very luck based. Try not to lose your mind if you just get REALLY unlucky. It happens :(

[Citizen 6508]

Right now i'm stuck on same place.
Even having characters with big amount of fortitude (500-600) i can't win, cause this characters don't fall asleep only first 2-3 times after sleep attack, after that they fall asleep anyway, and the boss just spams 5-7 turns with sleep and critical attacks.
Seems like this mechanic just broken.

P.S. Well, i win after ~10 hours of trying and rebuilding characters with U-rank team:

• Kaede
  • Fighting Spirit 10 lvl
  • Electric Paralyze 9 lvl
  • Absorb Focus 9 lvl
  • Cure Condition 10 lvl
  • Fortitude Up 10 lvl
• Himiko
  • Fighting Spirit 10 lvl
  • Ultra Defence 7 lvl
  • Electric Paralyze 9 lvl
  • Absorb Focus 9 lvl
  • Wind Barrier 9 lvl
• K1-B0
  • Fighting Spirit 10 lvl
  • Ultra Defence 10 lvl
  • Electric Paralyze 10 lvl
  • Absorb Focus 10 lvl
  • Wind Barrier 10 lvl
• Gonta
  • Fighting Spirit 10 lvl
  • Electric Paralyze 10 lvl
  • Absorb Focus 10 lvl
  • Cure Condition 9 lvl

Ultra Defence must be replaced on Cure Condition 10 lvl.

Also, Himiko weared next items for highest amount of fortitude and on this time she was the only one who resisted sleep:

• High Speed Staff
  
• Hard Worker's Hat
  
• Hard Worker's Uniform
  
• Hard Worker's Shoes
  
• Ultimate Artist Proof

Fortitude Up 10 lvl (Kaede) slightly help with prevent of sleep in complex with Cure Condition for reviving falling characters, cause last third of fight consisted of spam of sleep and crit attacks with killing of members my party. This is was very, very tiring.

Also, this is not optimal team and not solution, but can helps, i think.