Medusa is the best, of course, but I don't have her to experiment, and the forums killed the compendium, so I can't look up stuff
SL is really great, especially in a goon heavy pve like this last one. Once you have the strikes pumped up enough, you can pop his purples to wipe out an entire wave at a time in the longer nodes.
Peggy/IM40 is also really good, but often you finish the fight before you even get the black off, in which case, you'd probably be better off bringing a green AoE instead of carol.
Ghost Ridder might be pretty good, he fills the green slot that would be needed with peggy or SL, and the combination of the countdown doing direct damage and spawning an attack tile every turn would add up quickly. And then you can finish them with the green aoe. Actually, yeah, I'll need to try that if I ever get the 1 more cover I need to champ him. Which won't be any time soon, with him vaulted.
Coulson might be interesting with a spammy 3rd character. Pop one cooldown tile, and another takes it's place.
For an unorthodox suggestion, have you considered x-pool? His purple creates a LOT of CD tiles, and...well, I guess technically he has a red, even if it's not very good. Also, antman.
She also has good synergy with a number of 3* characters. IM40, as already mentioned. HT, BP, and maybe blade and punisher (though that's stepping on her black) for perpetual CD tiles, Lazy cap for recurrent ones, IF to get an attack tile and accelerate her black (and SW to power that too), and of course 3* hawkguy (or 5* if you're lucky enough) to spam the shit out of the CD tiles
If you have a 5* hawkguy with the passive, and preferably at least one of the actives, try him with coulson. It's ridiculous