In 616, Hulk left the Avengers after forming the group because he didn’t need ‘puny humans’

In 982, after Giant-Man brings up the point that no one is forced to stay on the team, Thor agrees he is not bound by oath and perhaps is not meant to fight alongside ‘mortals’

Giant- Man leaves due to an inferiority complex of not measuring up to the rest of the team

After trying to confront Hulk by himself and being unsuccessful, Iron Man retreats to repair his armor 

Hulk teams up with Namor who issues a challenge to the Avengers not knowing Iron Man is now alone. 616 happened the same way except with all Avengers present

After a failed attempt to get Rick Jones, Janet Van Dyne, and Hank Pym to wear Iron Man suits and help him, Iron Man goes to face the duo alone. Iron Man maximizes his armor

Iron Man does well but is ultimately no match until Rick, Hank, and Janet arrive in the suits and after Namor and Hulk gain the upper hand and maim Hank and Rick, Hulk gets angry and targets Namor for hurting Rick as Iron Man transfers the energy from his chest piece to Hank’s suit after being pummeled by the Hulk

After Namor and Hulk come to a stalemate and go their separate ways, Hank, Rick, and Janet mourn the loss of Tony Stark