Say I have Liepard active and Raikou-EX and Victini on my bench. I attack with Liepard's "Assist", flip heads and choose to copy Raikou-EX's "Thunder Fang" attack but flip tails for "Thunder Fang's" paralysis part. If I then use Victini's "Victory Star" Ability to re-flip the coins, assuming I get heads for "Assist" could I choose a different benched Pokemon's attack or would I have to choose "Thunder Fang" again?
Since Victory Star rewound all the coin flips it's as if the Assist attack never happened. So yes, you could choose a different benched Pokemon's attack, if you flip heads for Assist of course.
Source: TPCi Rules Team (2013-01-31)
If a Pokemon normally has no Weakness, does Vileplume's "Allergy Panic" Ability give it a x4 Weakness instead?
No, if a Pokemon doesn't have Weakness, you cannot *apply* any Weakness multiplier to it at all.
Source: Boundaries Crossed FAQ (2012-11-08), TPCi Rules Team (2012-11-08)
If I use Cresselia-EX's "Psychic Protection" attack, does Vileplume's "Allergy Panic" Ability override and give it a x4 Weakness instead?
No, since there is no longer a weakness there is nothing for Allergy Panic to multiply.
Source: Boundaries Crossed FAQ (2012-11-08), TPCi Rules Team (2012-11-08)
If a Pokemon normally has no Retreat Cost, does Jellicent's "Stickiness" Ability give it a Retreat Cost of (*) instead?
Yes, Stickiness adds +1 to each of the opponent's Pokemon's Retreat Costs. However, if the Retreat Costs are set to zero by an effect such as Darkrai-EX's "Dark Cloak" Ability, they cannot be increased by Stickiness.
Source: Boundaries Crossed FAQ (2012-11-08), TPCi Rules Team (2012-11-08)
If I have Ditto with "Transform" in play this turn, on my next turn can I put a Basic Pokemon from my hand on top of Ditto and then immediately evolve it into a Stage 1 or use Rare Candy to evolve it to Stage 2?
Yes, you can. Ditto says "Any cards attached to this Pokemon, damage counters, Special Conditions, turns in play, and any other effects remain on the new Pokemon"; so as long as Ditto has been in play for more than a turn it satisfies the evolutionary requirement, and the Basic Pokemon card placed on Ditto can be evolved or used with Rare Candy immediately.
Source: Boundaries Crossed FAQ (2012-11-08), TPCi Rules Team (2012-11-08)
Can you use Audino's "Busybody" Ability if there is no damage and no Special Conditions on your Active Pokemon?
No, you cannot. You have to heal something in order to use Busybody.
Source: TPCi Rules Team (2012-11-01)
If you have Flygon with "Sand Slammer" active, but the opponent has Serperior with "Royal Heal" in play, which Ability goes first? The one that places damage or the one that heals damage?
In this situation, the player whose Pokemon are being affected gets to choose the order of when the abilities take place.
Source: TPCi Rules Team (2012-11-01)
Can I use Empoleon's "Diving Draw" Ability if I have no cards left in my deck, and just discard a card from my hand?
Yes, you can. The first sentence of Diving Draw says to discard a card from your hand. Then if you can do that, you do as much of the rest of the Ability as you can, which in this case is draw no cards.
Source: TPCi Rules Team (2012-10-04)
If my opponent has Ampharos with "Electromagnetic Wall" in play, when I attach a Double Colorless Energy to one of my Pokemon, do I place 3 or 6 damage counters?
You place 3 because there was only one attachment, even though the attachment provided multiple energies.
Source: TPCi Rules Team (2012-09-13)
Would Emboar's "Inferno Fandango" Ability trigger Ampharos' "Electromagnetic Wall" Ability? Or does "Electromagnetic Wall" only apply to the opponent's normal once-per-turn energy attachment?
Any energies attached from the hand would trigger Electromagnetic Wall, regardless of whether they're attached due to an Ability or the normal once-per-turn energy attachment.
Source: TPCi Rules Team (2012-09-13)