We covered the rules of V-UNION Pokemon when they were first revealed back in June.
Four different cards form a V-UNION Pokemon. A V-UNION Pokemon can only be played to your Bench when all four cards are in your discard pile. Since all four cards of a V-UNION share the same name, you can only have one of each V-UNION Pokemon in your deck. When fully assembled, they’re neither Basic Pokemon nor Evolution Pokemon — their stage is “V-UNION.”
Now TPCi has posted an article that clarifies some of their trickier rules (we’ve edited some parts for clarity):
When the four cards are separate, they follow some tricky rules. When not in play, each piece of a Pokémon V-UNION still retains its Energy type (Grass, Fire, etc.), its card type (Pokémon), and its card name. So if you use Poké Kid, you could search for one of the four Pokémon V-UNION cards, since one piece is a Pokémon. You could also use Mysterious Treasure to search for a Mewtwo V-UNION card, since it’s a Psychic type. And if you have a Mewtwo V-UNION in your discard pile, you could use Familiar Bell to search for a Mewtwo V-UNION.
The other characteristics of a Pokémon V-UNION do not exist when it isn’t in play. For example, even if a Pokémon V-UNION has a Retreat Cost of 3 or more when it’s fully assembled, you still can’t search for any of the parts with Heavy Ball. And even though some parts have an HP listed, you still can’t search for them with Level Ball. The same goes for Abilities, Weakness, and so on.
The first V-UNION Pokemon will appear in the V-UNION Special Collections on September 24th for $29.99. Each will come with four promo cards of the V-UNION Pokemon, a jumbo card combining them into one card, a Professor Burnett Supporter card, four booster packs, and a PTCGO code card.