Frozone Cool Demeanor
Frozone’s freezes last 5 seconds longer if the target is above 25% of their max hp. When Frozone freezes an enemy, the freeze timer doesn’t start until all temporary buffs the target had when the freeze was applied expire. Frostbite now applies to allies’ freezes.
The 5 second duration increase has a chance to fail against enemies above level X.
Stat Boosts
+Hp
+Skill Power
+Damage per second to frostbite for every time an enemy has been frozen.
Rex mighty dinosaur
When an enemy without a shield would be healed, they instead receive a shield for 50% of the amount they would’ve healed. When an enemy has a shield, Rex has berserk. Rex heals X whenever a shielded enemy takes damage.
Stat Boosts
+max hp
+armor
+damage to shielded enemies
Miguel Rivera
Familia
When Miguel uses Crescendo, the ally with the least HP becomes invincible for 5 seconds.
Miguel’s notes each grant X Skill Power until the end of the wave when they’re removed.
+Max HP
+Basic Damage
+Skill Power from Serenade
Currently using his active does more harm for Miguel than it does good, so giving it the ability to buff and letting it protect the weakest ally would make him a lot more viable in auto modes.
Anyways, here is my idea for Scar’s red skill
On the Prowl
When Scar is “Prowling”, he may gain Z basic damage and 50% attack speed.
Scar may also deal a bonus Z damage with “A Matter of Pride” to silenced enemies.
Bonus damage may fail against enemies above level Z.
+~45% Max HP
+~120% Basic Damage
+~30% damage to Damage role enemies with “A Matter of Pride”
Sulley How you enter the room
Sulley scares enemies for 7 seconds at the start of every wave. Sulley takes 70% less damage from scared enemies and Sulley cannot be KOd by a scared enemy. Whenever Sulley gains skill power from scream power he also gains 15% attack speed up to a max of 200%.
The scare has a chance to fail against enemies above level Z.
Stat Boosts
+HP
+Skill Power given by Scream Power
Scream Power also gives x basic damage up to a max of Y.
Here are some ideas:
Megara
The first time Meg hits 1 HP, she regenerates her full health in 9 seconds and becomes invincible for 6 seconds.
Meg and her linked ally start the battle with 3 stacks of Hardy. This effect is level limited.
Additional Stats:
Jack Sparrow
“Pirate Code” now grants Jack 4-5 (which would be better?) seconds of invincibility and increases his attack speed by 75% for 10 seconds.
Jack also gains 300 energy every time one of his allies is K.O.ed. The energy gain is reduced for allies above level X.
Additional Stats:
Olaf
Olaf heals X HP per second while his blizzard from “On a Roll” is active.
Olaf’s basic attacks have a 50% chance to freeze targets for 7 seconds. The chance is reduced against enemies above level X.
Additional Stats:
Red skill ideas
Rafiki
It is time
The ally affected by “The past hurts” gain 75% attack and movement speed for 8 seconds.
Nearby allies gain 50% attack speed for 8 seconds.
Increased stats:
+X Max hp
+Y skill power
+Z more basic damage to the ally from “The past hurts”
Felix
Old classic
Every time Felix preforms a basic attack he gains X armor and 3 tenacity.
Increased stats:
+X Max hp
+Y Basic damage
+Z more skill power to allies from "Power of positivity
Hercules
Lucky stars
Hercules can’t be poisoned or take damage from D.O.T. When “True hero” activated Hercules heals nearby allies 75% of what Hercules heals.
Increased stats:
+X armor
+Y reality
+Z more damage to other tank enemies.
It already does that lol.
Oh.
I’ll fix that
Red skill for Dash
Mach Speed
Every 2nd time dash deals damage to an enemy, he grants a 20% speed buff to himself or a random ally for the rest of the wave. Dash cannot increase the speed of an ally with a 200% or higher speed buff.
Swift Strike hits 1 extra time for every 3rd time an ally has received a speed buff up to a max of 15 extra hits.
The speed buff has a chance to fail against enemies above level X.
Bonus Stat Boosts
+Max HP
+Basic Damage
+Damage per hit to Swift Strike
a better name would be “A True Original”
He already have red skill.
oh did not know that
Darkwing Duck red skill.
Shadow Strike
Whenever Darkwing becomes invisible by any source, he deals X damage to all nearby enemies and stuns them for 6 seconds. He also steals 20% of their armor and 15% of their reality and applies it to himself for the rest of the wave.
The armor and reality steal are less effective against enemies above level Y.
Bonus Stat Boosts
+Max Hp
+Armor
+Basic Damage given by shadow speed
Nights’ terror
“Shadow Speed” now doesn’t have any stack limits, and 50% of this bonus is carried between waves.
“Knockout” now removes all buffs from enemies, cooldown of “Shadow Stalker” is reduced by 1 second per each removed buff from enemies by “Knockout”.
Darkwing Duck receives less carried bonus from previous waves when his level is above level X.
Additional Stat Boosts:
The Happiest One in The Brain
Each stack of “Happiness” now gives 1% Conservation to herself and allies.
When Joy reach 10 stacks of “Happiness” for the first time in battle she gives shield from “Joy Bubble” and 2 stacks of Hardy to allies.
Shield have a chance to fail on allies above level X.
Additional Stat Boosts:
Perfect hustle
Finnick’s basic attacks freeze enemies for 6 seconds, each time Finnick freeze an enemy his skill power increase by X for remainder of wave.
“Jumbo Slam” now have increased attack range and damage all enemies, instead of only nearest ones.
The freeze has a chance to only last for 1.5 seconds on enemies higher than level X.
Additional Stat Boosts:
@Polaris could you look at this for a moment, and maybe pass this ideas to the team?
This could be extremely busted 
. Other than that, all 3 look fantastic.
To note, “Knockout” doesn’t hurt all enemies.
It might be not so clean, but only infected by this skill enemies lose their buffs.
Should I add it to post?
Still, if the cluster of enemies has a few buffs, he’s basically going invisible for the entire fight.
Or sometimes he will remove 0 buffs 
And during fight some enemies will die, reducing sources of buffs, making it harder to turn invisible.
And well, he’s terrible hero now, and require a lot of love 