Does using Lugia GX's "Lost Purge GX" attack count as KO'ing a Pokemon?
No, it does not. You are moving the opponent's Active Pokemon and all cards attached to the Lost Zone, and since it does not count as a KO you don't get to take any prizes for it.
Source: Lost Thunder FAQ (2018-10-20), TPCi Rules Team (2018-11-01)
If Blacephalon GX uses its "Mind Blown" attack to discard a Beast Energy as one of the Fire Energy discarded, does it still get the +30 damage bonus from Beast Energy?
Yes, it does. The energy cards are chosen, then Damage is calculated before the cards are sent to the Lost Zone.
Source: TPCi Rules Team (2018-11-01)
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)
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)
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)
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)
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)
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 my bench is full and I use Luvdisc's "Even Game" attack, does that allow me to exceed my normal bench size like Sky Field does?
Sorry, but no. You can't put more Pokemon on your bench than you are allowed to.
Source: Celestial Storm FAQ (2018-07-20), TPCi Rules Team (2018-08-02)
If Dhelmise does "Giga Drain" and the Defending Pokemon only has 10 HP left, does Dhelmise still heal itself for 30 damage?
Yes, because the 30 damage is still done, even though it is more than enough to KO the Defending Pokemon.
Source: Celestial Storm FAQ (2018-07-20), TPCi Rules Team (2018-08-02)