Ideas to inject some fun into the 5* tier

Kolence

I'll be sure to explain to my Wasp how she's perfectly well balanced with the rest of the 5's according to devs' budgets for powers the next time she returns home to my roster bloody nosed after trying to play with the cool kids in pvp.

ThaRoadWarrior

^^^ I would challenge the devs to treat every new 5* as somebody's transition 5* before they give it the greenlight. They don't all need to be more amazing than the last, but they cannot represent a net reduction in your ability to play the game over being a 4* player. That hypothetical transition roster in my mind is probably similar to what BBigler ended up with before tapping out - everybody rostered, about 1/3-1/2 the 4* tier champed, and then whatever this new character is going to be as a single champ.

I wonder if there is some sort all-AI pvp simulation they run on new/proposed characters to see how well they play that is just fundamentally not mimicking the actual player experience of single-5* MMR in the world?

Kolence

Here are some tweaks I've seen and really liked or came up with myself (so naturaly, also mostly like) that I think would be a step toward making 5-stars and pvp more balanced. 

A few 4-stars here as well, one that's perhaps troublesome even in 5-star play so it's fine, but the other two... are just so bad that I think it's ok. 

Oh, I apologize if it's clunky, or descriptions are inconsistent. Mostly done from a phone, and from several notes made at different times. ... And I'm too lazy these days to edit it much.


Thor (Gladiator)

God of Thunder - the same.
(PASSIVE) - the same, only add the 2nd condition - ...AND Thor is in front...

- At the start of each turn, if Thor is in front and below 50% health, destroys (number) basic red, green or yellow tiles.

Okoye 

Wakanda Forever! - the same. Just add a new passive effect to the list - ... For each enemy Okoye helps damage, destroy 1 friendly team-up AP also...

(PASSIVE) - Damage from friendly powers is incrased by (number) for each team-up AP you have. For each enemy Okoye helps damage, destroy 1 friendly team-up AP also. Okoye's base team-up damage is increased by (percentage). At the start of the turn, if Okoye is not in front, destroy 1 friendly team-up AP.

(These changes are imo a minor hickups for Thorkoye, one is meant to prevent Thor from hiding from a fight  and the other to slow them down a little on offense. Yes, I get that they're easy to beat on defense, but their speed on offense still reduces the choices for players)

Rocket & Groot (Awesome Mix Volume 2)

Welcome to the Team (PASSIVE) - Create 2 friendly strike tiles (3 if none are present) three times during the fight, once for each of Yellow, Blue and Green matches made as the initial matches on your turn. Stronger tiles paired with a Guardian. Start with 3 extra free tiles if all Guardian team.

(This makes it so Gritty starts with 0 strikes, and can only add 2-3, first 3 turns at the quickest, reaching 7 at most. Should give some time for other teams to prepare for it...)
(As a bonus, makes Grocket teams so much worse  on defense, as AI might miss making tiles by sheer dumbness)

Loki (God of Mischief)

Destroy Everything - the same, just add 
... If his Destroyer repeater tile is matched, Loki creates a copy of it on a random green basic tile. If his team matches it, he also reduces all other friendly repeaters by one. The copy starts fortified.

(This should allow multiple Destroyer tiles... unless that makes Loki/Carol too strong? If so, make it "matched away")

Captain Marvel (Galactic Warrior)

Mean Right Hook - fortify the repeater.

Event Horizon (PASSIVE) - at the start of combat and each turn after the CDs and repeaters have ticked, if there are fewer than 3, create up to 2 3-turn green repeater tiles that generate 1 green AP (max 3 of these tiles) so that each is at a different phase (3/2/1 turns left). If you match one, create 2 green strike tiles. If enemy matches one, drain 2 random enemy AP. 
With 10 or more green AP, turns into Photonic Rush and removes repeaters.

Photonic Rush - fortifies any friendly special tiles in the chosen row, then destroys that row and one more for every friendly tile that was fortified on the initial row. 
With fewer than 10 green AP, turns back to Event Horizon.

(strike tiles appear on basic green tiles)
(green Repeaters can spawn on any color tiles, like Wanda's CD)
(when spawning, it tries to be at 3 turns left. If already taken, tries 2 turns left, if taken it tries 1 turn left)
(This should help speed it up a bit, whenever a lower number repeater spawns before higher number ones, in the board order - above and to the left)
(If no repeaters were matched away, eventually it should settle to 6 AP every 4 turns, but just auto matches on spawning likely make it even faster)

Wasp (Hope Van Dyne)

(Swarm tiles are not locked here, just a unique special tile for Wasp, and can be fortified. Also, still neutral.)
(matching fortified tile still counts as a match, just sayin')

Sting Operation - Places a fortified swarm tile on a chosen color (random basic tile). 
(PASSIVE) - When you match a swarm tile, steal 1 AP of its color. If your team now has more AP than the enemy in that color, deal (tiny) damage for each swarm tile on the board (all in one tick). 

Shrink Tactics - Turns Wasp invisible for 3 turns and places 2 swarm tiles. Then, sends her allies airborne for 1 turn, plus 1 more for every 4 swarm tiles on the board.
(PASSIVE) - While Wasp is invisible, her matches do X% more damage for each swarm tile on the board.

Pain Index - Steal a burst of X health plus Y more per swarm tile on the board.
(PASSIVE) - Whenever a friendly special tile or a swarm tile is matched during Wasp's turn, at the start of her next turn she grows up to 3 swarm tiles creating another one on an adjacent basic tile to them. 

(ALL 3 POWERS PASSIVE PART) - When there are swarm tiles on each of the 6 colors or there are 12 swarm tiles on the board, all Wasp's powers become Call the Swarm.

Call the Swarm - Does X damage and destroys all the swarm tiles and 3 tiles around them (destroyed tiles do damage but no AP). 
(PASSIVE) - Revert powers back when there are fewer than 12 swarm tiles and there's a color without a swarm tile on it.

Emma Frost 

Girl's Best Friend - fortifies up to 6 friendly special tiles, adding (fortified) protect tiles if fewer are present, then turns into Diamond Skin.

Diamond Skin (PASSIVE) - Emma's match damage is increased (for real, like Ghost's) and she takes only 10% of damage from any source, BUT she can't fire powers. Removes fortification from friendly tiles when Emma takes damage - 1 tile for match damage, and half the tiles for ability damage. Creates a fortified purple attack tile when Emma makes a black match. Reverts back to Girl's Best Friend when there are no fortified friendly tiles present.

(not sure how fast she should be losing fortification, but definitely think there needs to be a reliable way to cap the duration)
(to be honest, not too hapy about tying it to fortified tiles, but might be there's a reason for that in some future character? idk...)

Sam Wilson (Captain America)
aka Flaptain, aka Failcap 

Wings of Liberty - creates a 2-turn Redwing drone repeater on a random basic tile, next to an enemy special tile when possible, that removes any enemy tiles in a 3x3 area around it and moves to a new tile, leaving a friendly protect tile in its place. If enemy matches it, recover X YELLOW AP. If you match it, destroy all enemy tiles in a 5x5 area around it.

Aerial Avenger (PASSIVE) - when your team makes a blue match, improve friendly s/a/p tiles, then decrease the number on one friendly repeater, AND increase the number on one enemy repeater.

(Not even sure Kity needs this, too be honest...)

Kitty Pryde

Phase and Conquer - the same. Just add another effect with enough tiles out - ... and then destroy one friendly s/a/p tile, if (threshold) or more are present. 

(meant to cap and/or stop her buffing after a point) 
(this threshold doesn't have to be the same or tied to her threshold at which she starts buffing tiles)
(so, there's room to fiddle with those numbers...)