I'm pretty sure you meant for its ability to boost Attack rather than Special Attack, right?
Ability: Pincer Rockets (Berserk clone; boosts Special Attack by 5 stages after falling below half HP as a result of an opponent's attack)
HP: 97 (+0)
Attack: 182 (+50)
Defense: 107 (+30)
Special Attack: 63 (+1)
Special Defense: 103 (+35)
Speed: 28 (-14)
New Moves: Mach Punch and Agility
Description: "In times of desperation, it can lop off its own pincers and fire them like rockets." Mega Crabominable can function as a devastating Agility sweeper thanks to Pincer Rockets; which if activated properly and used at the same time as Agility, can double Crabominable's Speed and give it a near-Belly Drum boost in one turn. However, even after an Agility, it barely manages to outspeed even Mega Pinsir. To fix the speed issue, it can be ran as a mixed Trick Room sweeper instead.