In Super Mario Kart I tend to use either Koopa Troopa or Toad since they seem to be the easiest to control in that game. In Double Dash I tend to use Yoshi and either Baby Mario/Baby Luigi, Koopa Troopa/Paratroopa, or Toad/Toadette to use their specials. In any other game I tend to just use Yoshi, although I also use other characters like Koopa Troopa, Ludwig, Larry, Lemmy, Toadette, and Luigi.