Can I use Indeedee's "Expert Nurturer" attack to evolve a Pokemon on the first turn of the game, or on the first turn that Pokemon came into play?
Yes, it can.
Source: TPCi Rules Team (2023-03-30)
If my opponent used Banette ex's "Everlasting Darkness" attack on their last turn, can I attach Vitality Band to my Pokemon on my turn?
Yes, Vitality Band is a Pokemon Tool card, not an Item card.
Source: Scarlet & Violet FAQ; TPCi Rules Team (2023-03-30)
If my opponent's Dolliv attacks with "Apply Oil" then on my turn I switch to a new Active Pokemon, do I still have to flip a coin to successfully attack?
No. Even though the effect references the opponent it was placed on "the Defending Pokemon", so the effect went away when you changed your Active Pokemon.
Source: Scarlet & Violet FAQ; TPCi Rules Team (2023-03-30)
If I use Medicham's "Acu-Punch-Ture" attack and the opponent switches to a different Active Pokemon that has the same attack as the one I chose for "Acu-Punch-Ture", can they use that attack?
The effect was on the Pokemon that was attacked, so if that Pokemon switches out the new Active Pokemon can use their attack of the same name.
Source: Scarlet & Violet FAQ; TPCi Rules Team (2023-03-30)
If my opponent has Arcanine ex or Gyarados ex on the Bench, will its "Tera" attribute prevent me from placing damage counters on it with Drifblim's "Curse Spreading" attack?
No, placing damage counters is different than dealing damage, so it won't be prevented.
Source: Scarlet & Violet FAQ; TPCi Rules Team (2023-03-30)
When I use Oranguru's "Primate Acting" attack and I realize I don't want to use any of the Supporter cards in my opponent's discard pile, can I choose not to use any?
No, you cannot. If you use the attack, you must choose a Supporter card if there are any in the discard pile.
Source: TPCi Rules Team (2023-01-19)
Can I use Oranguru's "Primate Acting" attack if I have already used a Supporter this turn?
Yes, you are not playing a second Supporter, you are just using the Supporter's effect as the effect of the attack.
Source: TPCi Rules Team (2023-01-19)
After using Unown VSTAR's "Star Cipher" attack while Path to the Peak is in play, I then use Spiritomb's "Ticking Terror" attack to change the Defending Pokemon's Weakness to {D}. If my opponent removes Path to the Peak from play, what will that Pokemon's Weakness be?
The Weakness will be {P}. Once Path to the Peak is removed from play Star Cipher's effect will reapply, and the most recent Weakness-changing effect takes precedent.
Source: TPCi Rules Team (2022-11-10)
If I use Unown VSTAR's "Star Cipher" attack while Dunsparce with "Mysterious Nest" Ability is in play, are my opponent's colorless Pokemon's Weakness set to {P} or do they have no Weakness at all?
The Star Cipher attack would switch your opponent's Pokemon's weakness to {P}, but then Dunsparce's Mysterious Nest would change all colorless Pokemon to no weakness.
Source: TPCi Rules Team (2022-11-10)
If my opponent has no Weakness and I use Unown VSTAR's "Star Cipher" Ability, will my opponent's Pokemon become weak to Psychic?
If an opponent's Pokemon has no Weakness printed on the card, Star Cipher will give that Pokemon a x2 Weakness to Psychic.
Source: Silver Tempest FAQ; TPCi Rules Team (2022-11-10)