Yoshi kid is one of Mario's partners in Paper Mario: The Thousand-Year Door. He is hatched from an egg in Glitzville, and can be renamed to the player's liking (there is also a timeframe to get different colored Yoshi such as pink, blue, etc). Although he may be small, this little guy has an attitude, and really packs a punch. Mario can ride on him and "flutter" across short distances (reminiscent of Parakarry from the first Paper Mario).
When Yoshi first joins Mario's party, he only has two moves: Ground Pound & Gulp. His Gulp ability is very useful when it comes to fighting enemies with spikes. Once upgraded to Super Rank, Yoshi learns the Mini-Egg move, which allows him to throw eggs at all enemies with the chance of shrinking them. Once upgraded to Ultra Rank, Yoshi learns the Stampede move, which allows him to summon a herd of Yoshi to trample all enemies.