Yea we're pretty lucky.
If you mean battle-wise, it's best to use physical victini as a choiced mon (Choice Band or Choice Scarf), so Victini can deal heavy damge then switch back in later to threaten to do some more, the one time item is a waste because Victini really needs the boosts.
AMERICA!!!
That works, but Stealth Rocks are a pain in Victini's butt-wings after switching so often.