Considering he can fly and is an agile, small target (and not at full home world strength to easily take down larger ship targets) my first thought is to toss Atom at the Steel Soldiers. If others are interested in forming a group for either of the optional goals, I'll gladly toss him at one of those- with preference to Shatter the Steel Soldier.

That said, I am flexible. If there's a prompt in need of more people, flying boy vs. flying enemy is a flying boy either way. lol

Atom can technically carry others, but is best as an option for carrying others away to safety, as a short-term option for lifting individuals between nearby ships, catching a falling individual, or even getting used to boost someone else's speed. He'll work fine with both those using armor or not.