For me, name, costume and powers have to have cohesion. Sometimes I come up with a cool costume and like to match powers and name, sometimes I have a good name idea and try to match powers and costum.
say... my latest, Blame Shifter... he just had to be a mind/time controller villain :) with a cheery blue/yellow costume and a gig red target on his chest. He started out with the name and a battle cry, and developed from there. This game deserves some whimsical 50s villains and heroes.
Or my Pistols/Poison corr, Deadeye sally. I wanted pistols, and her as natural, no strange energies. But.. traps again? Too many traps chars for me. Poison seemed to match RP wise, even though I was concerned at first after reading up on poison on the old forums that I might have created a true dud :(. Then I played her, in a team with 2 blasters, and after a bit of initial wrangling I was able to keep my team up and fighting very nicely, I just had to adjust what I did to whom and when. So, debuffs first on spawn, then out come the guns.
Now its a very fun to play char who throws around toxins, poisons her foes and finishes them off with her six-guns.