All right, I'm bringing Genji/Roadhog/Reinhardt/McCree/Reaper/Lucio

Wasabi is completely outclassed by Genji's speed and ability to fight in range and melee, so he's easily out.

Roadhog focuses his hooks on stopping GoGo. Even if he fails, she's really not that dangerous IMO. Lucio can probably 1v1 her if necessary, he has similar mobility but also a gun, which she lacks.

Fred gets instantly shredded by either Reaper or Roadhog. Reaper can use wraith or teleport to avoid the flame breath and get in close, and Roadhog can either hook him or tank through it.

Honey Lemon would pose a threat if not for Rein, who can totally shut her down by blocking her with his shield.

Hiro is ez

Baymax could pose a threat due to his tankiness and the only real damage output besides Wasabi, but McCree can 1v1 him if he stays in the air, and if he gets close to the ground, he'll get shredded by our tank killers Reaper and Hog.

Even if their abilities are on par, which I don't think they are, they don't have nearly as much experience as an Overwatch team, they're locked into only six skill sets, and Hiro is pretty much useless, unless I'm forgetting something from the movie. That gauntlet is staying where it is.