If I use Arceus' "Type Switch" attack and choose a type, what happens if I use Ninja Boy to switch Arceus for a Basic Pokemon of a different type? Does the new Pokemon become both types or does the new type supersede the choice from "Type Switch"? Or what if you Ninja Boy for a dual-type Pokemon like Volcanion EX that is Fire/Water?
The type chosen by Type Switch overrides the Pokemon's actual type, so the new Pokemon would become the type chosen rather than its regular type. And in the case of a dual-type Pokemon it would become the single type that you chose for Type Switch.
Source: TPCi Rules Team (2017-12-21)
I'm confused by the text on Peeking Red Card. After the opponent shuffles their hand into their deck, who gets to draw that many cards, the opponent or me?
The opponent gets to draw that many cards.
Source: Crimson Invasion FAQ (2017-10-20), TPCi Rules Team (2017-11-02)
Can I use Heavy Ball to search for Wimpod that has the "Wimp Out" Ability on my first turn?
Yes, you can. Abilities only work when in play (unless the card says otherwise), so Wimp Out is not active while Wimpod is still in the deck.
Source: TPCi Rules Team (2017-09-14)
Can I play Guzma if my opponent doesn't have any Pokemon on their Bench?
No, you cannot. If the opponent doesn't have a bench there's no way to do the second part of the trainer, and you cannot play a Trainer card for no effect.
Source: TPCi Rules Team (2017-08-31)
If I use Guzma and choose my opponent's Primal Groudon-EX that has the "Omega Barrier" Ancient Trait, do I still get to switch my own Pokemon?
Since Omega Barrier prevents the first effect of Guzma, you do not get to switch your Pokemon.
Source: TPCi Rules Team (2017-08-31)
Can I play "Acerola" to return a damaged Pokemon and all cards attached to it to my hand when Lunatone's "Heal Block" ability is activated?
Yes, you can return the Pokemon and attached cards to your hand.
Source: Burning Shadows FAQ (2017-07-20), TPCi Rules Team (2017-08-03)
If I use Eelektrik's "Small Appetite" attack against a Pokemon with 90 HP but it has the "Bodybuilding Dumbbells" Pokemon Tool attached, do I do 50 damage or 0?
You do 0 damage. The HP from Bodybuilding Dumbbells counts toward the Pokemon's maximum HP, putting it out of range of the Small Appetite attack.
Source: Burning Shadows FAQ (2017-07-20), TPCi Rules Team (2017-08-03)
If I play "Guzma", who chooses which Pokemon to switch for each player?
You make all of those choices.
Source: Burning Shadows FAQ (2017-07-20), TPCi Rules Team (2017-08-03)
Can you play Captivating Poke Puff if your opponent's Bench is full?
No. It's public knowledge that you can't put down any additional Basic Pokemon on your opponent's Bench, so you cannot play the card.
Source: TPCi Rules Team (2016-08-11), TPCi Rules Team (2017-08-03)
Can I use Brooklet Hill to search through my deck even if my Bench is full?
No. Since your Bench is already full it's public knowledge that Brooklet Hill won't have any effect, so you cannot search your deck.
Source: TPCi Rules Team (2017-06-27)