Keldeo Water and fighting. Unique~
I don't know who is the best, but I like Scrafty, Infernape, Mienshao, Heracross and Breloom.
Considering that there is another Water/Fighting since Generation I, it is not that unique:
[img139]http://cdn.bulbagarden.net/upload/6/67/Spr_1b_062.png[/img139]