Tornadus (Incarnate Forme)

The first member of the Forces of Nature... exists. A very unspectacular moveset cripples its ability to compete against other Flying types, despite its respectable ATK stat. Beyond this, it would take a huge buff to Hurricane or some other form of rebalancing to let it top the Flying charts.

On the bright side; we finally get to see the Flying Type background, as Tornadus - Incarnate was the first Pokemon with Flying as a primary type. Now all that it needs is access to Bleakwind Storm.

Best PvE Offensive Moveset

• Air Slash and Hurricane go together to make Tornadus a Flying Type attacker
• Bite and Dark Pulse can make for a Dark Type attacker, though it's not good in that role.
• Grass Knot and Hyper Beam are not worth considering on Tornadus.

Air Slash takes advantage of STAB and provides decent energy generation. Bite can be more preferable depending what coverage is needed, but the lack of STAB and very poor energy generation makes it less optimal overall. 

Grass Knot is a strong charge move and covers Rock-type Pokemon that Tornadus is weak to, along with common Water Pokemon. Dark Pulse provides relatively neutral coverage against various meta picks across all three leagues, but can be particularly useful in formats such as Open Ultra League. Hurricane is quite strong with STAB, but has an expensive energy cost that Tornadus can't generate comfortably with its fast moves. For that reason, Hyper Beam is also not recommended.