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M-Pinsir gets countered easily by Smogonwasher and dies to a lot of stuff. The x4 and x2 stealth rocks hurts too. Unlike megas like Mawile or Lucario is can't really jump in whenever it wants and fuck over everything in its path.
However, when brought out at the correct time late game, when you've cleared out a lot of your opponents choices, it can literally take out half the team itself. Trash over Return is more of a hail mary and usually means you're going for a one time rampage of OHKO's, as it can completely break through any non-resisted defense unlike any unboosted pokemon I've ever seen. However, Pinsir enjoys being able to use its coverage move and its priority if the situation requires it.
