Mr. Yeti is a main character in Candy Crush Soda Saga. He appears in the first episode, Candy Town. He also is from the original game, making him the first character from Candy Crush Saga to be in Candy Crush Soda.
He points out some helpful tips if you are having trouble with levels.
In Candy Town, he concerns of the "disappearance" of Tiffi, and why her letters suddenly stopped coming.