What happens if I use Morpeko V's "Electro Wheel" attack but I don't have any Benched Pokemon?
You still have to discard an Energy if you can, but since there are no Benched Pokemon to switch with, Morpeko V stays in the Active Spot.
Source: Sword & Shield FAQ (2020-01-24), TPCi Rules Team (2020-02-06)
Can I use Grapploct's "Octolock" attack to a new Defending Pokemon if the previous one switches out?
If you use the attack again, yes. You just can't apply more than one Octolock effect to the same Defending Pokemon.
Source: Sword & Shield FAQ (2020-01-24), TPCi Rules Team (2020-02-06)
Grapploct's "Octolock" attack says its effect can't be applied more than once. What does that mean?
It means that if the Defending Pokemon is already under the effect of Octolock you cannot do it again for an additional {C}{C} cost. In other words, it does not stack.
Source: Sword & Shield FAQ (2020-01-24), TPCi Rules Team (2020-02-06)
Say I have Keldeo GX already in play, and my opponent uses Latios GX's "Clear Vision GX" attack with Power Plant in play. If I play a different Stadium to get rid of Power Plant, can I use Keldeo-GX's "Resolute Blade GX" attack now?
Yes, you can. When Power Plant is removed Keldeo GX's Pure Heart Ability turns back on, and Keldeo GX is no longer hit by the global effect of Clear Vision GX. If an attack does not place an effect on Keldeo GX directly, like an attack that puts an effect that isn't removed when returning to the Bench, it can be removed by reactivating Pure Heart.
Source: TPCi Rules Team (2020-02-06)
If a player has some face up prize cards from using Blacephelon's "Blazer" attack and then takes a multi-prize knockout, do they take their prizes one at a time or must they take all of them at once?
Whenever you take more than one prize in a single action, each prize can be taken one at a time.
Source: TPCi Rules Team (2020-01-09)
Does Channeler negate the effects of Arceus & Dialga & Palkia GX's "Altered Creation GX" attack?
It depends on who is playing the Channeler. If the player who used Altered Creation GX uses Channeler then the effects are removed; the player's Pokemon no longer do +30 damage and the player does not get to take any extra prizes from the effect. However, if the player's opponent plays Channeler, then Altered Creation GX effects are not removed as they reside on the other player (who did not play Channeler).
Source: TPCi Rules Team (2020-01-09)
If I use Mimikyu's "Impersonation" attack to discard an opponent's Whitney, does that Whitney count for the "draw 2 cards for each other Whitney in your Discard Pile" because you're not actually playing that Whitney, just using its effect?
No, you still cannot count that Whitney towards the number of cards to be drawn because its text only includes any OTHER Whitney in your Discard Pile.
Source: TPCi Rules Team (2019-12-05)
When using Mimikyu's "Impersonation" attack, can I discard a Supporter like Green's Exploration or Morgan and bypass the requirement that says you can only play the Supporter if you do such-and-such?
You can discard those types of Supporter cards with Impersonation, but if you don't meet the Supporter card's requirements you cannot do what is says.
Source: TPCi Rules Team (2019-12-05)
What happens if I put a Keldeo GX with "Pure Heart" Ability into play after my opponent has used Latios GX's "Clear Vision GX" attack? Would my Keldeo GX be able to use its "Resolute Blade GX" attack or not?
As long as the Pure Heart ability is not blocked or turned off when Keldeo GX comes into play, it would be unaffected by Clear Vision GX.
Source: TPCi Rules Team (2019-12-05)
If I have a single Rainbow Energy attached to Moltres & Zapdos & Articuno GX, can I use the extra effect of its "Sky Legends GX" attack?
No, even though Rainbow Energy provides all energy types simultaneously, it only provides one unit of energy. You can use it for either the Fire or the Water or the Lightning, but you still need additional units of energy for the other required types.
Source: TPCi Rules Team (2019-11-14)