This one is simple. Just register a local rank leaderboard score with each of the three characters in characters.
Technically, you don't have to play, because it's a 2 minute game, and you only need to get 100,000 points to get top of the leaderboard, and you can get that in two seconds at the start of the game by firing. Anyway, as soon as you register the third score, this achievement will pop.