I'm using characters from video games I played as a kid. Right now I'm using the Mario series. Mario, Luigi, Peach, Toad, Bowser, Yoshi, ... Then I'll use another video game series or maybe just mix them all up and go in no order. Sonic, Tails, Zelda, Link, Leonardo, Splinter, Donkey Kong, Diddy Kong, Kirby. If I ever run out, I'll just go to the endless Pokemon list.