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)
My opponent and I both have Sudowoodo with "Roadblock"Ability in play. I use Hex Maniac on my turn to shut off "Roadblock", and then I play 5 Pokemon on my Bench. My opponent plays 5 Pokemon on their Bench during their turn. At the end of my opponent's turn, Hex Maniac's effect ends, so "Roadblock" activates again. Who discards their Pokemon first? If the first player discards their Sudowoodo, would the other person need to discard a Benched Pokemon?
It's the opponent's turn, so their Roadblock goes into effect first. You would discard your Pokemon first, and then your opponent would discard theirs. Even if you chose to discard your Sudowoodo, your opponent would have to discard down to 4 Benched Pokémon because the Roadblock effects happen simultaneously.
Source: TPCi Rules Team (2017-05-25)
When using Potion, 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: TPCi Rules Team (2017-05-18)
When using Rough Seas, can I choose to heal only some of my {W} and {L} Pokemon or do I have to heal all of them?
If you choose to use Rough Seas you must heal all {W} or {L} Pokemon with damage counters on them.
Source: TPCi Rules Team (2017-05-18)