There are 3 basic strategies here for what this team is about: cheap or bulk CD production, cheap or bulk special production, or just generally cheap powers allowing Coulson to be the CD maker.
Additionally characters who can add Team Up tiles to the board are helpful here (really I think that’s just 2* Captain Marvel and Okoye), or barring that to collect them on powers like 3* Storm because Coulson can burn those down to shorten CDs.
3* Partners
Loki - allow enemy match-4s to get ridiculous CD spam that also steals AP. Use his black to flip any opponent strikes/defends to the opposite as you steal them
Patch - play with Loki to generate enemy strikes along with friendly, and get double action. Play up with Medusa and get more AP gain, health regen, or stolen tiles for your trouble
Sentry - you will be hard pressed to get more active CD spam from a character than you get from Sentry, but be aware nobody is coming out alive if you do…
Daken - free strike spam on green, very cheap blue that can keep Coulson spitting out CDs even though it’s removing friendly strikes. Your mileage may vary here
Blade - passive strike creation and active attack creation, used to be better when his black was a short CD pre-repeaters
Hawk3ye - cheap powers, all CD based for the most part, true heal, can create friendly strikes
4* partners:
W4sp has long been the golden 3rd on this team. bank up 8 blue, hilarity ensues.
Medusa - constant CD on the board, health regen whenever a friendly special is matched, chase your own CD to split it down into attack tiles as often as you can
Worthy Cap seems like the obvious but overlooked choice on your list. Eat enough damage, flood the board with red/blue and 1-turn CDs
Valkyrie - always has a CD in play, if teammates take damage she spits out strikes
Magik - creates defend tiles on friendly fire and fortifies existing specials - maybe not the most useful
Kingpin - You might not think it, but Kingpin/Coulson/C4rol is a decent team. KP’s CDs hit harder than coulson’s I believe, and they don’t blow up the board, so use Coulson to shorten KP’s CDs in the background.
Ronin - free red attack spam, cheap green
I’m sure there are plenty more, these are just the ones I can think of.
Also - if you have him even remotely usable, 5* Hawkeye is another one.