Can I play Fiery Flint if I only have 1 card in my hand to discard?
No, you must be able to discard 2 cards in order to use Fiery Flint.
Source: TPCi Rules Team (2018-09-27)
Can I use Dragonite GX's "Dragonporter GX" attack to place a Stage 1 or Stage 2 Dragon type Pokemon directly onto my Bench?
Yes, you can. Per the attack, you are not limited to Basic Pokemon.
Source: TPCi Rules Team (2018-09-27)
What happens if you use Rayquaza GX's "Stormy Winds" Ability, but can only discard less than 3 cards from your deck? Do you get to attach a basic Energy card from your discard pile to Rayquaza GX or not?
If you can discard at least 1 card from your deck, you can use the Ability and attach a Basic Energy card from your discard pile. If you can't discard any cards, you can't use it.
Source: TPCi Rules Team (2018-08-16), TPCi Rules Team (2018-09-06)
Does using Beast Ball count as "taking a prize" for the purpose of calculating damage for Stakataka GX's "Assembly GX" attack?
No, it does not. You are switching cards, not taking a prize.
Source: TPCi Rules Team (2018-08-16)
Say I have taken 5 prize cards during the game, but then my opponent uses Naganadel GX's "Stinger GX" attack to bring both players' prize count back to three prizes remaining. So if I then use Stakataka GX's "Assembly GX" attack on my next turn, how many prizes would I count when calculating the amount of damage to be done?
Even though the Stinger GX attack added cards back into your prizes, you have still taken five prizes during the game. So Assembly GX would do 50 damage plus 250 (five times 50) for the prize cards you have already taken.
Source: TPCi Rules Team (2018-08-09)
Sky Pillar says, "Prevent all effects of the opponent's attacks, including damage, done to Benched Pokemon (both yours and your opponent's)". So does this mean if I use an attack like Zapdos' "Raging Thunder" that I do not apply the bench damage to my own Pokemon?
No, only bench damage done from an opponent's attacks is prevented by Sky Pillar. If your attack does damage to your own Benched Pokemon it is not prevented.
Source: TPCi Rules Team (2018-08-09)
Does Venusaur's "Jungle Totem" Ability boost the damage output of Rayquaza GX's "Dragon Break" attack since "each Basic {G} Energy attached to your Pokemon provides {G}{G} Energy"?
Yes, just because the Basic Energy card is now providing two units of energy doesn't change the fact that it's still Basic Energy.
Source: TPCi Rules Team (2018-08-09)
If Voltorb is attacked by Blastoise EX's "Rapid Spin" which pushes it to the Bench after doing damage, do you still flip for Voltorb's "Destiny Burst" Ability or not?
Yes. Destiny Burst checks for two things: Voltorb was damaged by an attack while it was your Active Pokemon, and Voltorb was Knocked Out by that attack. So even though you don't check for a KO until the attack is completed, the criteria for using Destiny Burst has been met, so it can be used. This holds true for any similar Ability that triggers when the Pokemon is Active and gets damaged by an attack.
Source: XY FAQ (2014-02-06), TPCi Rules Team (2014-02-06), TPCi Rules Team (2018-08-09)
If I use Gladion and choose to put Jirachi {*} into my hand, can I use Jirachi {*}'s "Wish Upon a Star" Ability?
Sorry, but Wish Upon a Star only triggers when you are taking it as a face-down prize card, not when you are trading it with another card.
Source: TPCi Rules Team (2018-08-02)