[trg]

Originally Posted by Fat Admiral Bobbery

No, but Tyranitar can take RP Genesect down after it has set up.

+1 252+ SpA Life Orb Genesect Giga Drain vs. 252 HP / 252+ SpD Tyranitar in sand: 161-190 (39.85 - 47.02%) -- guaranteed 3HKO

So Genesect even at +1, Modest, and Life Orb, can only 3HKO Tyranitar, but Tyranitar can hit back.

0- SpA Tyranitar Fire Blast vs. 0 HP / 4 SpD Genesect: 312-368 (110.24 - 130.03%) -- guaranteed OHKO

If Tyranitar carries Fire Blast, then it can live a Giga Drain or two and KO back. It's not an all around hard counter to Genesect, but the Rock Polish set can't really touch it. Note, that calc is done with the Special Attack boost and Life Orb. If Genesect is Life Orb, it's much harder to keep its set hidden from your opponent, meaning that you might even already know its set before you have to resort to Tyranitar, and you can kill it a different way. Most RP Genesect have Expert Belt instead, which does:

+1 252+ SpA Expert Belt Genesect Giga Drain vs. 252 HP / 252+ SpD Tyranitar in sand: 149-175 (36.88 - 43.31%) -- guaranteed 3HKO after Stealth Rock

And if Genesect doesn't get the Special Attack boost:

252+ SpA Life Orb Genesect Giga Drain vs. 252 HP / 252+ SpD Tyranitar in sand: 107-127 (26.48 - 31.43%) -- guaranteed 4HKO after Stealth Rock

252+ SpA Expert Belt Genesect Giga Drain vs. 252 HP / 252+ SpD Tyranitar in sand: 98-118 (24.25 - 29.2%) -- possible 4HKO after Stealth Rock

So no, Tyranitar isn't a foolproof Genesect counter, but it can certainly counter the Rock Polish set even if it has already set up.

Those are nice calcs and all, but they still do nothing to prove T-Tar is a good check to Sect in general since you could potentially be eating a strong U-Turn.

That's like saying Slowbro is a reliable check for Scizor since it resists Bullet Punch.