Abilities » Victory Star
Can I use Victini's "Victory Star" ability to reflip just the tails flips from an attack?
No. You must reflip all of the flips for an attack if you use Victory Star.
Source: Noble Victories FAQ (2011-11-17), PUI Rules Team (2011-11-17)

Relevant cards

Note: All applicable cards may not be listed below.
BW11_23
BW3_14
BW3_98
BWP_BW32
BWP_BW32
SM2_10