Terrakion

Terrakion is a very versatile and strong attacker that has a good base 108 Speed and base 129 Attack, which let it outspeed and easily KO threatening Pokemon such as Mega Charizard X and Mega Charizard Y. It also checks dangerous attackers, especially Dark-types such as Bisharp, Tyranitar, and Weavile, and its Rock / Fighting typing gives it a nice resistance to Normal-type moves such as Fake Out and Extreme Speed. Not only that, Terrakion has access to priority in Mach Punch, which lets it finish off weakened threats. Terrakion has access to almost no viable coverage moves bar Iron Head, but it doesn't really need coverage moves to be usable, as it has access to Close Combat and Diamond Storm, both of which are boosted by STAB and have almost perfect neutral coverage. However, Terrakion has a bad defensive typing that leaves it weak to common attacking types in Fighting, Ground, Fairy, and Psychic. Adding onto that, Terrakion also has mediocre 91 / 90 / 90 bulk, which means it can easily be KOed by a lot of common threats in STABmons, such as Landorus-T, Mega Lopunny, Mega Scizor, and Keldeo. Terrakion is also KOed really quickly due to the fact that it commonly uses Life Orb, and the prevalence of priority users in STABmons makes it difficult for it to stay healthy.