If my Tyranitar GX knocks out an opponent's Glaceon GX with the "Freezing Gaze" Ability, does Tyranitar GX's "Lost Out" Ability turn on in time for it to send Glaceon GX to the Lost Zone?
Nope, Freezing Gaze is still active when Glaceon GX is KO'd, so Tyranitar GX does not get to use its Lost Out Ability.
Source: TPCi Rules Team (2018-12-27)
When using Shedinja's "Vessel of Life" Ability is the underlying Nincada discarded, or does it get attached as part of the Pokemon Tool?
The Nincada is discarded; only the Shedinja card gets attached as a Pokemon Tool.
Source: TPCi Rules Team (2018-12-27)
Say my opponent has a Sudowoodo with the "Roadblock" Ability on his bench, but it's currently disabled due to my active Alolan Muk's "Power of Alchemy" Ability. If I have five Pokemon on my bench when Alolan Muk gets KO'd and "Roadblock" becomes enabled, do I have to discard one of my five benched Pokemon before promoting a new Active Pokemon or not?
When you remove your Active Pokemon after resolving all effects that caused it to be KO'd, you must replace it immediately before resolving any other new effects that take place.
Source: TPCi Rules Team (2018-12-06)
If I use Sylveon's "Wink Wink" attack to have my opponent discard Ilima, can I use Victini's "Victory Star" Ability to force my opponent to re-flip their coins?
Yes, you can. If your opponent flips a coin as part of your Pokemon's attack, you can use "Victory Star" to force them to re-flip those coins; but keep in mind you will have to re-flip your coins for Ilima too.
Source: TPCi Rules Team (2018-11-15)
How does Slaking's "Lazy" Ability or any other form of Ability denial that only applies to Pokemon "in play" interact with Abilities like Giratina's "Distortion Door" Ability that puts a Pokemon card from the discard pile onto your bench?
Since Distortion Door happens when Giratina is not in play, you can use it to put Giratina onto the bench regardless of Lazy or other similar Abilities. You also get to put the damage counters onto your opponent's benched Pokemon too, because you must complete the action of Distortion Door prior to it being shutoff due to Lazy.
Source: TPCi Rules Team (2018-11-15)
Can you evolve Ditto {*} into a Stage 1 Pokemon and then on a later turn place a new, different Stage 1 Pokemon onto it?
No, not unless you have devolved Ditto {*} somehow during a previous turn.
Source: Lost Thunder FAQ (2018-10-20), TPCi Rules Team (2018-11-01)
If I have placed a Stage 1 Pokemon onto Ditto {*}, can I later evolve that into the corresponding Stage 2 Pokemon?
Yes, you can!
Source: Lost Thunder FAQ (2018-10-20), TPCi Rules Team (2018-11-01)
Can you choose to not Confuse your opponent's active Pokemon if you attach Fairy Charm to a Tapu Lele that has the "Charmed Charm" Ability?
Yes, it is optional.
Source: Lost Thunder FAQ (2018-10-20), TPCi Rules Team (2018-11-01)
What happens if I use Skiploom's "Floral Path to the Sky" Ability but fail to find a Jumpluff in my deck?
Skiploom stays in play, and since you searched your deck the ability is used up for the turn.
Source: Lost Thunder FAQ (2018-10-20), TPCi Rules Team (2018-11-01)
What happens to any damage counters on Skiploom when it uses its "Floral Path to the Sky" Ability? Do they go on the Jumpluff that takes Skiploom's place?
Any damage counters on Skiploom are removed when it goes to the Lost Zone; they do not transfer to the Jumpluff that takes its place. Special conditions are not transferred to the new Jumpluff either.
Source: Lost Thunder FAQ (2018-10-20), TPCi Rules Team (2018-11-01)