>>17534698>+2you're not always going to get a swords dance off against a forretress. Even if you do, it will live with sturdy, force you OUT with red card while it sets up stealth rock, hurting you the next time you switch in.
252 Atk Aerilate Mega Pinsir Return vs. 252 HP / 252+ Def Forretress: 141-166 (39.8 - 46.8%) -- guaranteed 3HKO after Leftovers recovery
That's without an SD. Meanwhile, Forretress is going to be setting up rocks all over you, and when you hit it, you'll activate it's red card and be forced out. The next time you switch in, you'll take 50%. Forretress wins.
0 SpA Mega Pinsir Hidden Power Fire vs. 252 HP / 0 SpD Forretress: 184-220 (51.9 - 62.1%) -- 98% chance to 2HKO after Leftovers recovery
Running Naive with no special attack investment nets you a nice surprise KO. Forretress may set up stones, but that's all it will do.