a thing which could be fun if got added
you know the myth in B/W where Ho-oh appears in the tower if you rang the bell 3 times. Imagine if it got added not obtainable but battle able
or other myth pokemon's like keldeo, Heatren, Darkrai, Arceus, Mew, Celebi etc.
just for the fact that we have a chance to at least battle them to make them appeard in our pokedex hehe