Yoshi
Yoshi, since 1991, has been Mario's steed, from whence he was a baby (superMario World 2: Yoshi's Island) and even as an adult (Super Mario World).
Yoshi is from the world of the Mushroom Kingdom along with Mario, Peach, and Luigi. He's a dinosaur of some sort. Early on he made weird sounds but now he speaks with a kind of voice. He can use his tongue to his advantage and can throw eggs very expertly.
As mentioned, Yoshi started his career in the hit Super Nintendo game Super Mario World, where he was a constant companion to Mario and Luigi. However, more of his past, or possibly his parent's life came to light in Super Mario World 2: Yoshi's Island, where he became a full-fledged video game hero with his classic Yoshi sound and egg throwing.
Roleplaying Difficulty: Expert
Yoshi is a very cowardly character. Besides being featured in his own game, Yoshi also appeared in the animated Super Mario Brothers show from years past.
However, he does not have much depth, so the one that chooses him must be creative.