The cool thing about Tornadus-Therian is that you have Hurricane + 3 moveslots that you can pick whatever your team needs the most, the moves that Tornadus-T can run, can be run together without many drawbacks and they work on both AV and LO sets (though some obviously work better on LO sets)
Tornadus-Therian @ Assault Vest
EVs: 132 HP / 160 SpA / 216 Spe
Timid Nature
- Hurricane
- U-Turn
- Knock Off
- filler
Looking at the usage stats this is the most common set. It is a very good switchin for pokemon like Latios, Landorus and Gengar and it is able to grab momentum directly after switching in, almost losing nothing because of Regenerator. The most used filler move is Heat Wave, but HP Ice and Superpower are also worth a mention (don't run Timid when Superpower)
Tornadus-Therian @ Life Orb
Ability: Regenerator
EVs: 76 Atk / 216 SpA / 216 Spe
Naive Nature
- Hurricane
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With the 3 empty spots I am not saying you should only spam LO Hurricanes, but that there are many options that can be used to help the team the most. Knock Off and U-Turn are again by far the most used coverage moves, but one of them can be dropped for extra coverage because you have an option in mainly Focus Blast or Superpower and Heat Wave for the last slot, and some teams may prefer both coverage moves. HP Ice is also a move that gets surprisingly much usage (29%) so that is definitely also a good option to consider.
I see Tornadus-Therian often paired on bulky offensive teams with pokemon like Keldeo, Mega Altaria and Scizor as teammates, as Tornadus-Therian can punch holes in the walls (LO) clean late game (LO / AV) or be an excellent offensive pivot (AV and LO to a lesser extent) for these teams. Tornadus-Therian is not really a pokemon you build around, but it is a pokemon you put on a team if it needs a good offensive pivot, wallbreaker or cleaner and the flexibility of the coverage moves makes it a very good glue. It doesn't need very much support, as Regenerator helps with the Stealth Rock weakness and finding a resist to ice and rock type attacks isn't that difficult with a tier full of steel types, though the LO set might want some hazards control because LO + Stealth Rock can still wear Tornadus-T down.