If I'm using Scizor's "Punishing Scissors" attack and one of my opponent's V Pokemon has Forest Seal Stone attached, does my attack do an extra 50 damage for it?
No, the V Pokemon does not *have* the Star Alchemy Ability, it only can use it.
Source: TPCi Rules Team (2023-09-28)

Relevant cards

Note: All applicable cards may not be listed below.
SV3_141
SV3_141
SWSH12_156
SWSH12_156