Well, the Orre game can be considered odd for other reasons. They had a completely different artstyle and the characters in the English and Japanese versions had weird names (and in one case, an unfortunate one).I loved the Stadium and Orre games, although I wouldn't call them odd. They use main series mechanics, after all.
I really liked Magikarp Jump too! It's one of those games you check into every few hours when you're on the bus or between classes.Magikarp Jump kind of ruled. It was basically a normal Pokemon game but every Pokemon was a different variation of Magikarp. And I loved decorating. It even had a ghost girl, thus cementing itself as a real Pokemon game to me.