2* Hawkeye pairs very well with both 2* Magneto and 2* Captain Marvel as they can both help set up match-5's to get Hawkeye's Purple passive (easily his best Power) going.
Colossus is unfortunately not a great character, so you probably don't want to roster him just yet. Luke Cage is much better and covers the same colors, he'd be my priority to keep if you could save a Three-star cover.