Tornadus (Therian Forme)

Tornadus Therian Forme is actually the weaker version of its Incarnate Forme, unlike Landorus and Thundurus. Having access to Bleakwind Storm does give it an edge over its Incarnate counterpart, however (at least for the time being). With this move, Tornadus Therian Forme isn't too shabby as a Flying attacker choice, though it remains outclassed by many.

Best PvE Offensive Moveset

• Gust benefits from STAB and suits Tornadus's role as a Flying-type attacker.
• Astonish has no use.
• Bleakwind Storm*, Tornadus's signature move, is its best available option
• Hurricane is mediocre, but can be used if Bleakwind Storm is unavailable.
• Psychic is okay if no Charge TMs are available. 
• Heat Wave and Focus Blast have no use. 

Gust hits hard with STAB, and provides decent energy gains. Astonish is astonishingly mediocre.

Bleakwind Storm is Tornadus-T's cheapest Charged Attack and provides a useful guaranteed Attack debuff. Focus Blast is extremely expensive, but it provides situational coverage against Steel-, Rock-, and Electric-type Pokemon. Hurricane is largely redundant because Gust and Bleakwind Storm already provide good STAB Flying-type damage. Heat Wave is a poor move. Psychic is a rather underwhelming attack and provides inconsequential coverage.