Abomination - Have him be able to poison with basic attacks. Make his chance of poisoning the opponent like 25% when hitting them. Have it stack.
Ant Man - Make his poison stronger please. Give his level 1 and 3 specials are reason to be used. That's all honestly lol.
Black Bolt- Joel Lines Video
https://www.youtube.com/watch?v=sjWpkIvcNXk
Black Panther (Classic) - Make his bleed stronger. I really love BP in this game one of my favorite characters to play but I noticed after the 12.0 update that his bleed was weaker. If I recall correctly his bleed pre 12.0 was doing at least 100 damage a tick. Now its doing 79 a tick.
Daredevil (Netflix) - Idk what needs to be done with him but I know he needs a buff for sure.
Deadpool X Force - Have his bleeds be able to stack up to 4 or 5. Give him a power gain at 75%, 50%, and 25% increasing it the lower he gets. Like 75% he would only fill a bar of power, 50% he would fill 2 bars, and at 25% he would fill 3 bars of power.
Dr. Strange - Buff his regen just a little bit please. He's still good I'll admit but he's a shell of his former self. (Maybe that's because of the comics

)
Gamora - I love Gamora in this game already but she need a little tweaking. I say let her assassination be able to proc throughout the fight not just once. If not this give her a regeneration because she has an accelerated healing factor. Doesn't need to be a crazy regeneration like Wolverine or anything maybe something along the lines of Cables Regen but not as long I guess to balance her. Make her special 3 worth using too.
Groot - First for Groot make him Poison Immune too. I don't understand why he can be poisoned lol. Also make his level 1 special be able to armor break or something. That would be nice.
Joe Biscuit - Idk how to fix him but he's needs tweaking with his Sig ability and his bleed lengths.
Kamala Khan - Oh man she is a tricky one. Kamala has potential but is outclassed by the other Ms. Marvels. Kamala has 2 things Shapeshifting and a Healing Factor. Since she struggles to control her powers because she cant do both have it be that way in the game. If you want a regen you have to deal with hitting like a wet noodle. If you want the damage she should hit about as hard as Spiderman does.
Loki - Needs Medical assistance for how many times I body this dude for free. Idk how to fix him but he needs something more around his curse ability. It's unique and I like it.
Luke Cage - Make him resistant to bullets. Like reduce the damage done by bullets by like 80% (War Machine Special 1, Punisher Special 1 & 2, Winter Soldier Special 1 & 2 Joe Biscuit Special 1)
Make his indestructible proc every 10-15 hits either dealing damage or taking damage. Make Him hit almost hard as Iron Fist. Remember Luke Cage is PowerMan. Give him a fury too.
Punisher 2099 - Fix his damage output. Take the numbers from when he has an armor break on the opponent and make those the normal numbers.
She Hulk - Delete her from the game. >:^(
Nah but give her a perma regen like Old Man Logan at a set rate. Raise her stun chance up on specials since that's where most of her damage comes from.
Special 1 55%
Special 2 65%
Special 3 75%
Spider Gwen - FIx it Jesus

If I left anyone off this list that needs fixing leave them in the comments. I want to see other peoples fixes.