Skeleton T, as his name implies, is a living skeleton; the "T" in his name references his obsession with Japanese tea. He is the first opponent in the original Puyo Puyo's beginner mode, and is therefore the weakest character in the game. He is notorious for his simple AI, which will never take advantage of the ability to rotate the currently-controlled pair of Puyo.
In Kirby's Avalanche , he is replaced by a generic Waddle Dee. Dr. Robotnik's Mean Bean Machine removed the beginner course, therefore Skeleton T's AI is not represented in the game.