Drone Rotom says, "Your opponent reveals their hand. If they do, look at the top card of your opponent's deck." But what happens if the opponent doesn't have any cards in their hand?
If there are no cards in your opponent's hand, you can't play Drone Rotom in the first place.
Source: TPCi Rules Team (2021-01-21)
If I play a Pokemon with the "Top Entry" Ability and it goes to the bench as a Stage 1, what happens if I then use Devolution Spray Z?
You can't use Devolution Spray Z on it since although it is an "Evolution Pokemon", it is not Evolved because there is no Basic underneath it. Either you can't play the card, or if it has already been played (it's no longer in the hand) another target will have to be chosen. If there are no other legal targets, then the play has to be reversed.
Source: TPCi Rules Team (2021-01-21)
When using Alolan Raichu's "Electro Rain" attack or Hoopa GX's "Devilish Hands GX" attack with a Telescopic Sight tool attached, would Telescopic Sight boost the damage to Pokemon-GX and Pokemon-V each and every time I choose that Pokemon?
Per the rule book you make all your choices first, calculate the damage, then apply modifiers (such as Telescopic Sight), and then apply damage to the chosen Pokemon. So you would not get to add +30 more than once if you choose the same Pokemon again and again; however if you choose multiple Pokemon-GX or Pokemon-V, you would get to add +30 to each of those.
Source: TPCi Rules Team (2020-12-10)
If I play Lysandre {*} when my opponent has Shiftry's "Shifty Substitution" Ability in effect, does Lysandre {*} go to the Lost Zone or not after it has been played?
Shifty Substitution does not affect the Prism Star rule, so Lysandre {*} would go to the Lost Zone.
Source: TPCi Rules Team (2020-12-10)
Does Moomoo Cheese allow you to heal 30 damage each from up to 2 of your Pokemon, or does it heal a total of 30 damage between the two (like 20 on one and 10 on another)?
Each Pokemon you choose for Moomoo Cheese gets to heal 30 damage.
Source: Vivid Voltage FAQ (2020-10-31), TPCi Rules Team (2020-11-12)
When using Moomoo Cheese, can I choose to heal less than 30 damage from my Pokemon?
If the Pokemon has 30 or more damage on it you must heal 30 damage, but if it has less than 30 damage you do as much as you can and heal all of it.
Source: Vivid Voltage FAQ (2020-10-31), TPCi Rules Team (2020-11-12)
For Billowing Smoke, since prize cards are discarded when the Pokemon it's attached to gets KO'd, how does this interact with Dubwool V's "Revenge Blast" attack that "does 30 more damage for each Prize card your opponent has taken"?
Revenge Blast does not count any prizes that were discarded due to Billowing Smoke.
Source: TPCi Rules Team (2020-10-22)
If I play the Will supporter that lets me choose heads or tails for my first coin flip of an attack, do I get to use Will's effect again if I use Glimwood Tangle stadium to reflip the coins?
Yes, if you use Glimwood Tangle, Will lets you choose heads/tails for the first coin of the reflip.
Source: TPCi Rules Team (2020-09-24)