For me, I already like the Grass/Steel type, Nattorei. Base stats of Nattorei: HP: 74 Atk: 94 Def: 131 Sp Atk: 54 Sp Def: 116 Spe: 20 Ability: Iron Barbs (What does it do? But it sure sounds spiky... it'd better learn Spikes.) Considering Nattorei only has a weakness to Fighting and Fire, as well as high defenses on both ends, it can pretty much wall anything with a neutral attack on both ends if given the right EV spread, and it if can learn Synthesis, or even better, Recover, it just makes it sweeter. And it's attack is high enough for it not to be set-up fodder and with it's low speed and Steel-typing, Gyro Ball will be doing insane damage, that's if it learns it, which it better does, or else. And Power Whip, or at least Seed Bomb, would also be a move that Nattorei should be able to learn, and it is very useful to smack around Swampert and other bulky Grounds, which Forretress has no hope of doing without Explosion. It sounds like it can learn Spikes as well. Forretress is so replaced now.