1. Unown
Introduced in the second generation with great plans, Unknown and its 28 different forms have devolved into nothing more than a gimmick with a myriad of shapes you would only catch all of if you were really intent on catching em all. It's weak, it resembles letters, it makes mysterious stuff hard to read and they can only learn Hidden Power, a move which ALL other pokemon can learn. Basically, a good idea, ultimately evolving into a waste of space.
