I've said it before, his low speed and poor defensive typing is irrelevant to his ability to trap and kill checks. He is removing your checks, not sweeping, so those factors are completely irrelevant. Wobbuffet had poor Speed and didn't have the best defensive typing either. If we ban Tyranitar, we have at least made some of Mence's checks more viable, such as Cresselia (Don't bring up Scizor, Cress can deal with him with HP Fire), and stuff like Scarf Gengar and Starmie aren't AS weak to Pursuit (Yes, Scizor can Pursuit them, but Scizor is nowhere near as resilient as TTar when talking about Special Attackers like Gengar and Starmie). Cresselia would have more opportunities to heal with Moonlight (Although Hippowdon might come up in usage, I guess), so Mence isn't going to smack through her as easily. Removing TTar would suddenly make Mence's checks so much easier to use, and such, Mence wouldn't be as bad.