OMNintendo

Blue Beetle Blue Beetle's living suit provides him with an insane amount of power and I think it would overwhelm base Iron Man. If given time, Tony would develop a suit that could battle Blue Beetle.

Team Doctor Strange (Classic) Doctor Strange, Hulk and Thor would wipe the floor with most of the Justice League. Iron Man Bleeding Edge suit could also cause massive damage.

Oblivion Oblivion would use telepathy to render Thanos motionless then use his death touch and kill him