I use Iron Fist with Rising Fang, Hawkeye with Quicksilver, and Doom with Plasma Beam. It’s a pretty straightforward team.
Iron Fist can use the Quicksilver assist to cover his unsafe rekkas, while also nullifying pushblocking so he can open people up. Once he starts a combo, he can activate the meter gain chi; if he keeps the opponent grounded, one of his meter gain bnbs can get 213% meter solo (more if you count the arrow hits, and even more if you add plasma beam somewhere, but I haven’t gone in the lab with that yet). What’s cool about Iron Fist is that while you’re just moving around trying to get in, you can activate his defense chi and take 20% less damage for 5 seconds. Once he gets in, it’s up to you to either go for damage or meter, depending on how much of a problem the first enemy character is. Once you get a ton of meter, you can DHC into Gimlet after a combo (from Iron Rage) to get Hawkeye in.
I went with Plasma Beam for Doom instead of Hidden Missiles because, in my opinion, it’s a much more reliable assist. Hidden Missiles has a lot more total frames than Plasma Beam, and since it goes straight up before it comes back down, it means that the gap Hawkeye leaves in his offense after doing an arrow special leaves both characters vulnerable. Any character with high ground mobility can easily get in and put on their birthday hat. Iron Fist can tag both characters from full screen with two wavedashes canceled into s.M, for example.
Using Plasma Beam means that you can cover both horizontal and vertical space. The constant threat of that assist is gonna make people want to jump, where they eat guaranteed chip (as opposed to the guessing game you have otherwise). If they can’t close the distance while Doom is out, depending on their maneuverability, they might avoid the missiles anyway. I know I’ve eaten combos while missiles hit the ground harmlessly behind the enemy.
At mid-screen, with Hawkeye out, you can hold your ground by calling Rising Fang if you have it. It serves a lot of purposes: covering the diagonal space in front of Hawkeye, destroying any low-priority projectiles it meets (even mutual nullification for medium ones), and causing a wallbounce on hit, which can be confirmed into Hawkeye’s s.H, qcf+M loop combo. If Taskmaster jumps, does an aerial spidey swing canceled into M arrows, Rising Fang will beat it clean. You can probably even wavedash into a slide and do a full combo instead of the ranged one.
Doom is a monster of an anchor on any team, so he’s fine where he is.