When using Froslass' "Spiteful Sigh" attack, can you put more damage counters on Froslass than it has remaining HP?
Yes, you can.
Source: Unified Minds FAQ (2019-07-19), TPCi Rules Team (2019-08-01)
If my opponent has used Latios GX's "Clear Vision GX" attack, can I use a GX attack that ignores effects?
No, because you don't even get to start using the GX attack.
Source: Unified Minds FAQ (2019-07-19), TPCi Rules Team (2019-08-01)
Can I use Garchomp & Giratina GX's "GG End GX" attack to remove all of my opponent's Pokemon from play?
Yes, if your opponent only has 1 (or 2, with the extra energy) in play, you could remove those Pokemon. Then you win the game!
Source: Unified Minds FAQ (2019-07-19), TPCi Rules Team (2019-08-01)
If Reshiram & Charizard GX has the extra 3 Fire Energy for "Double Blaze GX's" bonus effect and attacks a Whimsicott GX with "Fluffy Cotton" Ability, does the Whimsicott GX get to flip for "Fluffy Cotton" or does the "Double Blaze GX" attack go through automatically?
Technically speaking you still flip for Fluffy Cotton, but regardless of the flip's outcome the Double Blaze GX attack ignores the effect and does the damage anyway.
Source: TPCi Rules Team (2019-06-27)
If I have Focus Sash attached to Marshadow & Machamp GX and then use its "Acme of Heroism GX" attack, which one takes precedence if Marshadow & Machamp GX would be KO'd by damage from an opponent's attack?
You would choose, as they have the same effect, you choose the order of resolution.
Source: TPCi Rules Team (2019-06-27)
If my opponent has no Weakness and I use Meowstic's "Perplexing Eyes" attack, will I do extra damage on my next turn due to Weakness?
If a Pokemon has no Weakness printed on the card, Perplexing Eyes will give that Pokemon a x2 Weakness to Psychic.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-02), TPCi Rules Team (2019-05-16)
If I have Celesteela GX with "Force Canceler" Ability active, what happens if my opponent uses Venomoth GX's "Ten-Card Return GX" attack?
The damage portion gets blocked, but your opponent still gets to shuffle their hand into their deck and draw 10 cards because that part is not being done to YOUR Pokemon.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-09)
When I use Meowstic's "Perplexing Eyes" attack does it change my opponent's active Pokemon's weakness before I do damage?
No. Do damage first, then apply effects.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-02)
If I had used Muk & Alolan Muk GX's "Severe Poison" attack that places extra Poison damage counters and in the next turn use Koga's Trap, do they still place the extra Poison damage?
No, they don't. The new, normal Poison Special Condition replaces the old Severe Poison Special Condition.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-02)
If I Switch my Active Pokemon that is affected by Poison from Muk & Alolan Muk GX's "Severe Poison" attack and Dust Island is in play, does my new Active Pokemon take the extra damage counters?
Yes, it does. Dust Island specifies that it is affected by "that Special Condition".
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-02)