Aquaman. Super strength, breathing underwater and swiming as fast as a jet flies, at that point commanding blue whales is just a perk.
Gambit. Turning literally anything into an explosive, how can you not see the use in that?
Stretching (elongated man, mr. fantastic, plastic man). Mobility is extremly useful as is being able to take a shot and no absorb any of the impact. Plus being able to punch someone from a distance they would need a gun, lots of good.
Atom. He can infiltrate places others cannot. He can get into machines and sabotauge them. Plus, as his crazy ex-wife proved he could get into your brain, increase his mass just a little and fucking kill you.