Other Options

Tornadus-T can use Taunt in conjunction with its high Speed to shut down opposing setup sweepers, prevent entry hazards from being set, or stop defensive Pokemon from using status or recovery moves. Similarly, Toxic is an option to cripple opposing Pokemon and limit their effectiveness. Sludge Bomb can be used on more offensive sets to better hit Clefable and Tapu Koko. Superpower is an option to surprise specially defensive switch-ins like Heatran as well as Tyranitar while hitting more consistently than Focus Blast. Weather Ball can be used on hail and sand teams primarily to provide strong coverage against Zapdos while otherwise being a decent neutral attack.

Checks and Counters

Electric-types: Tapu Koko, Zeraora, and Zapdos can all easily threaten Tornadus-T with an OHKO or 2HKO while easily taking hits from it. Arctozolt also outspeeds Tornadus-T in hail and OHKOes it with Bolt Beak. Most of these don't like switching into Knock Off and can be pivoted out of with U-turn, but Zapdos in particular can punish Tornadus-T with Static.

Weavile: Weavile in particular is threatening to Tornadus-T thanks to outspeeding it if running a Jolly nature and doing significant damage with Ice Shard if running Adamant, though it can't switch into Tornadus-T due to its weakness to U-turn and overall frailty.

Specially Defensive Pokemon: Tornadus-T struggles to meaningfully damage most specially defensive Pokemon if not running Superpower, and Heatran and Melmetal are notable for taking very little from its attacks and doing significant amounts of damage back, though it can significantly reduce their longevity by removing their Leftovers with Knock Off.

Stealth Rock: Tornadus-T is weak to Stealth Rock, which makes Regenerator less effective and leads to it either relying on Heavy-Duty Boots or needing a teammate that can either remove entry hazards or absorb Knock Off.