Can I play Acro Bike if there's only one card left in my deck? And if so, do I put that one card into my hand or discard it, or do I get to choose?
You can play Acro Bike with only one card left in your deck; but you have to put it into your hand, you cannot discard it.
Source: TPCi Rules Team (2019-10-31)
Can you choose the order of effects when playing a Tag Team Supporter, or do you have to do them in the order stated on the card?
You must do them in the order stated on the card. However, you don't have to meet the criteria for the first effect in order to do the second effect; for example, if the first effect says to search your deck but you don't have any cards in your deck you can still do the second effect as long as you meet its criteria.
Source: Cosmic Eclipse FAQ (2019-10-18), TPCi Rules Team (2019-10-31)
If I use Charizard's "Recall" attack to use Charmeleon's "Slash" attack, do I need to have the required energy cost to use "Slash"?
No, Charizard just needs the one energy required to use Recall. You do not need to meet the energy requirement from the previous Evolution's attack, but if that attack requires you to do something with energy (like discarding an energy card) you must follow that attack's instructions.
Source: TPCi Rules Team (2016-02-11), Cosmic Eclipse FAQ (2019-10-18), Cosmic Eclipse FAQ (2019-10-31)
If my opponent used Magnemite's "Mirror Shot" attack last turn, and I try to use my GX attack this turn and flip tails, do I lose the ability to use a GX attack for the rest of the game?
No, because since you flipped tails the attack "doesn't happen".
Source: Cosmic Eclipse FAQ (2019-10-18), TPCi Rules Team (2019-10-31)
What happens if my bench is full when I use Wishiwashi GX's "Massive Catch GX" attack? Can I put down more Pokemon than I would normally have space for on my bench?
Sorry, but no. You can't put more Pokemon on your bench than you are allowed to.
Source: Cosmic Eclipse FAQ (2019-10-18), TPCi Rules Team (2019-10-31)
If I'm not allowed to play a Supporter card for some reason, can I still use Mimikyu's "Impersonation" attack to use the effect of a Supporter?
Sure. You are not playing the Supporter, just using its effect.
Source: Cosmic Eclipse FAQ (2019-10-18), TPCi Rules Team (2019-10-31)
If I use Mimikyu's "Impersonation" attack, do I get to use the "when you play this card" part of Tag Team Supporters or not?
Impersonation gets to use all effects of the card; you still do the entire part of the card even if you're not "playing" it (but you still have to pay any required costs).
Source: Cosmic Eclipse FAQ (2019-10-18), TPCi Rules Team (2019-10-31)
Do I have to take any cards from my deck if I use Charizard & Braixen GX's "Brilliant Flare" attack?
It says "may", so you can choose to not search your deck; but if you do search you must take at least one card from it.
Source: Cosmic Eclipse FAQ (2019-10-18), TPCi Rules Team (2019-10-31)
When I use Arceus & Dialga & Palkia GX's "Altered Creation GX" attack do I take an extra Prize card only if I Knock Out that Active Pokemon with an attack, or do I take an extra Prize for ANY of my opponent's Active Pokemon that get KO'd by my attacks during the rest of the game?
You get to take an extra prize if your Pokemon's attack Knocks Out ANY of your opponent's Active Pokemon during the rest of the game, not just the one that was the Defending Pokemon at the time of the Altered Creation GX attack.
Source: Cosmic Eclipse FAQ (2019-10-18), TPCi Rules Team (2019-10-31)
For Wishiwashi's "Scatter" Ability, when does this check for damage counters happen, before "in between turns" when Poison counters are placed or afterward?
After your opponent concludes their end of turn actions including all effects of attack and cleaning up any KO, then before in between turns you check for any damage counters on Wishiwashi that would trigger Scatter to shuffle Wishiwashi and all cards attached into your deck.
Source: Cosmic Eclipse FAQ (2019-10-18), TPCi Rules Team (2019-10-31)