Elephant Steve is a member of the Avengers. It’s implied that he’s a recent member, since Giant-Girl mentions that he hasn’t gotten used to Iron Man‘s egotism like the rest of them.
During the “Iron Avengers” story arc, he gets offended by Iron Man’s self-centered nature (humorously, at first Iron Man thought Steve was angry because he had used the “elephant in the room” phrase) and storms off into the kitchen to complain to Jarvis while eating pie. He later arrives just in time to save the Avengers from Ultron.
In a later story, Hawkeye tries to borrow his laptop. He intends to trade it for magic beans, but tells Steve that he wants to write a movie. Unfortunately for Hawkeye, the “movie” is too similar to real life (a superhero with no powers on a team with other heroes) including Hawkeye’s true intent, so Steve refuses.
Powers and Abilities
Elephant Steve is super-strong. He once defeated Ultron with a single punch.
He also has a highly accurate memory, being able to recall the exact time and date Ultron had once said he would next attack the Avengers. (Though it’s inaccurate to say he never forgets, since he mentions that if that were true he would’ve mentioned it the day before)
He also owns a laptop. It’s unknown how he’s able to type on it if he had elephant hands.
Iron Man had once built him his own suit of armor along with the other Avengers (and later the X-Men and Ka-Zar) but Elephant Steve had stormed out of the room before he could reveal this, so the suit was never used.