Say I have an Yveltal with "Fright Night" Ability as my Active Pokemon with Bursting Balloon attached, then I play Hex Maniac. What happens at the end of my opponent's turn, when they attack and do damage to Yveltal?
Hex Maniac works until the end of your opponent's turn. At the end of your opponent's turn, you check to see if Bursting Balloon gets discarded. So Bursting Balloon places the 6 damage counters, Hex Maniac's effect wears off, and then Fright Night is reactivated preventing Bursting Balloon from being discarded.
Talonflame's "Gale Wings" Ability says if it's in your hand when you are setting up to play, you may put it face down as your Active Pokemon. If your opening hand has no Basics but you do have Talonflame, you can choose to put it out as your Active OR show you have no basics and mulligan... YOU DECIDE.
Source:
Steam Siege FAQ (2016-08-04), TPCi Rules Team (2016-08-04)
If Bronzong with the "Metal Fortress" Ability is in play, are benched Pokemon protected from Greninja's "Shadow Stitching" attack? If so, does it also protect Pokemon that come into play on the bench during the opponent's turn?
If Bronzong is on the Bench, all benched Pokemon are protected, including ones put into play after the attack has happened (for example, Shaymin-EX's "Set Up" Ability will work in this scenario); however, the Active Pokemon is not protected, even if it goes to the Bench it will not get its Ability back. If Bronzong is Active and has its Metal Fortress shut off, the Benched Pokemon are not protected; even if it moves to the Bench, it will not get its Ability back. Finally, if Bronzong is on the Bench and becomes the Active Pokemon during your turn, it loses its Ability and the Benched Pokémon are no longer protected.
Suppose that I have a Gourgeist with the "Gourgantic" Ability, with a Grass Energy and Heavy Boots attached and a Training Center in play. Would its max HP be 200 or 250?
Gourgantic essentially replaces Gourgeist's printed HP, so reductions and additions to HP work as normal. You can stack the additional HP effects of Heavy Boots and Training Center, so in this case the resulting HP would be 250.
What happens if I try to use Ho-Oh EX's "Rebirth" Ability but my bench is full? Is the Ability used up, or is it not used and I can try it again later after I have some space on my bench?
If you know the Ability will not affect the game state, you cannot use it. If your Bench is already full, you cannot use Rebirth.
If Marowak's "Bodyguard" ability is in effect, preventing the effects of attacks on me and my hand, does Greninja's "Shadow Stitching" attack turn off abilities of Pokemon in my hand or not?
Shadow Stitching turns off the Bodyguard ability, so until the end of your next turn none of your Pokemon will have Abilities.
If a Pokemon with Bursting Balloon tool attached is attacked by an Yveltal with the "Fright Night" Ability no damage is placed on the attacker, but is the tool discarded at the end of the turn as its text indicates?
The Bursting Balloon damage placement effect is turned off, but the discard text is also an effect, so the tool is not discarded at the end of the turn.