For Xerneas' "Power Creation" attack, do I need to heal all damage from Xerneas in order for the attack to do +80 more damage, or can I just heal some damage in order to get the benefit?
As long as you have healed any damage from Xerneas this turn, you get the bonus damage effect.
Source: BREAKthrough FAQ (2015-11-19), TPCi Rules Team (2015-11-19)
For Swoobat's "Returning Echo" attack, if it is my only Pokemon in play do I have to flip a coin for the attack?
Yes, and if you get tails your Swoobat will leave play and you will have no Pokemon remaining on the field.
Source: BREAKthrough FAQ (2015-11-19), TPCi Rules Team (2015-11-19)
What happens if Mewtwo EX uses its "Damage Change" attack against a Pokemon that blocks effects of attacks? Does nothing happen, or does Mewtwo EX get to remove its damage counters?
Mewtwo-EX would remove its damage counters, but the opponent's Active Pokemon would not remove nor receive any. If you try to move damage *to* something that blocks effects, the damage disappears. If you try to move damage *from* something that blocks effects, the damage stays there.
Source: TPCi Rules Team (2015-10-29)
What happens if Zoroark uses its "Foul Play" attack to copy Haxorus' "Dragon Dance" attack? Would it apply to Zoroark or not (because its name is not Haxorus)?
Zoroark's Foul Play can choose Dragon Dance, but since its name is not "Haxorus" the attack will basically have no effect. Dragon Dance specifically refers to Haxorus, so any Pokemon not named Haxorus cannot receive the damage boost.
Source: TPCi Rules Team (2015-10-29)
If I attach a Grass energy from my hand using M Sceptile EX's "Jagged Saber" attack to a benched Malamar EX, will I be able to use Malamar EX's "Hyper Hypnosis" Ability to put my opponent's Active Pokemon to sleep?
Yes, you can. An Energy is being attached from your hand to Malamar-EX, so Hyper Hypnosis can be used.
Source: TPCi Rules Team (2015-10-29)
Can I use Sableye's "Bewitching Eyes" attack to copy my opponent's "Archie's Ace in the Hole" or "Maxie's Hidden Ball Trick" supporter?
Yes you can, as long as you meet the requirement of having no cards in your hand when doing so.
Source: TPCi Rules Team (2015-09-17)
If I use Mega Sceptile EX's "Jagged Saber" attack against Giratina EX with the "Renegade Pulse" Ancient Trait, does Mega Sceptile EX's "Theta Stop" Ancient Trait prevent "Renegade Pulse" from blocking the damage? If not, then does "Renegade Pulse" prevent "Jagged Saber" from attaching any Grass Energy?
Renegade Pulse prevents all effects of attacks done to Giratina EX, but it does not "do anything" to Mega Sceptile EX for its Theta Stop to kick in. So the damage part is blocked by Renegade Pulse, but the effect of attaching energy is not being done to Giratina EX so that part of the attack does not get blocked.
Source: TPCi Rules Team (2015-09-03)
Does Golurk's "Superpower" attack apply Resistance to the +20 damage it does to itself?
Yes, as long as Golurk is Fighting Type at the time of the attack, Resistance would be applied.
Source: Ancient Origins FAQ (2015-08-13), TPCi Rules Team (2015-08-13)
Can I use Close Encounter after my first turn, or only during my very first turn of the game?
You can use it on any turn, including your turn if you go first (when you normally would not be allowed to attack).
Source: Roaring Skies FAQ (2015-05-07), TPCi Rules Team (2015-05-07)
Both players have 1 prize left. Player-A uses Jirachi's "Doom Desire" attack. Player-B attacks Jirachi with enough damage to KO it with the same Pokemon that got hit by "Doom Desire". Who wins? Or is it a tie?
The KO from Player-B's attack happens before the end of his turn, so the game is over before Doom Desire's effect gets to happen. Player-B wins.
Source: TPCi Rules Team (2015-05-07)