Stealth Rock is the probably the only thing seriously hindering his durability, really. Without it, Weavile usually only gets OHKOed by super effective physical attacks and really strong special attacks. Not even Flygon's Outrage or Gengar's HP Fire will do it. Extremespeed Dragonite is going to be annoying, but not much else since it has four-moveslot syndrome and can't KO it at 75% even if it has max Attack. It could prove to be a problem if it has a Dragon Dance up, though.
Other than that, Weavile can find plenty of switch-in opportunities against the stuff he's supposed to check, since they're usually either defensive, slower and Pursuit weak, or just plain lacking in the power necessary to KO him.
Other than that, Weavile can find plenty of switch-in opportunities against the stuff he's supposed to check, since they're usually either defensive, slower and Pursuit weak, or just plain lacking in the power necessary to KO him.