LEGEND Pokemon - Pokémon Rulings Compendium

Can I use Heavy Ball to look for a LEGEND Pokemon half?: No, you cannot. The Retreat Cost is only printed on one half of the LEGEND Pokemon. If it is printed on both cards, then it is a common attribute for both pieces; but since it is printed on only one half it only applies to the LEGEND Pokemon when both pieces are in play.

Source: TPCi Rules Team (2012-04-05)

If "Raikou & Suicune LEGEND" attacks "Suicune & Entei LEGEND", how is weakness calculated?: Since "Suicune & Entei LEGEND" is weak to both of "Raikou & Suicune LEGEND's" types (Electric and Water), you would multiply the damage x4.

Source: Unleashed FAQ (2010-05-13), PUI Rules Team (2010-05-13)

Do the LEGEND cards with two Pokemon on them (i.e. "Entei & Raikou LEGEND", etc.) count as two Pokemon while in play?: No, they only count as a single Pokemon when in play, even if your opponent takes 2 Prize cards when they are knocked out.

Source: Unleashed FAQ (2010-05-13), PUI Rules Team (2010-05-13)

Can I use Mew's "Re-creation" attack to choose a Lugia LEGEND card with the attack "Elemental Blast" written on it from my opponent's discard pile, and use that attack?: No, you can't use any attacks from a Pokemon LEGEND unless both pieces are in play.

Source: PUI Rules Team (2010-02-18)

If Primeape's "Top Drop" attack reveals a LEGEND Pokemon card with no HP printed on it, how much damage does it do (if any)?: No damage is done regardless of which LEGEND half is revealed by Top Drop, because even the half with HP written on it is not considered "a Pokemon" while in the Discard Pile.

Source: PUI Rules Team (2010-02-04), PUI Rules Team (2010-02-18)

Can I use Mantine's "Group Swim" attack to put one half of a Lugia LEGEND card in my hand?: Yes. Either half of the Lugia LEGEND card is still considered "a Water-type Pokemon", so you can search for it with Group Swim.