Hmm, what about a CB set?
Victini @ Choice Band
Adamant Nature (+Atk -SAtk) or Jolly (+Spe -SAtk)
252 Atk/ 252 Speed/ 4 Defense (342 is divisible by 4, limiting its switch into SR)
Fairly simple set that tries to hit hard, although I doubt it will be successful since it speed ties with other base 100 pokemon, forcing it to run jolly for the Speed ties.
I could also see the possibility of a Bluff Expert Belt Set
Victini @ Expert Belt
252 Atk/ 180 Speed/ 76 Sp. Atk (or whatever spread it is that jirachi runs)
-- Fire Blast/Flare Blitz
-- Grass Knot/Brick Break
-- Wild Bolt/Thunder
Fire Blast/Flare Blitz for obvious STAB. U-Turn helps bluff a choice item if you use it early on. Grass Knot is there to hit the heavy bulky waters and Ground types. Brick Break is there should you use the specially based Spread but have issues with blissey. Wild Bolt/Thunder choice of opposing moves to hit bulky water types that aren't part ground.