When using Radiant Greninja's "Concealed Cards" Ability, can I discard an Energy card from my hand, and then later during my turn draw 2 cards?
No, you must draw the 2 cards immediately after discarding the Energy card. "Once during your turn" means you cannot use this Radiant Greninja's Concealed Cards Ability multiple times during the same turn.
Source:
Astral Radiance FAQ; TPCi Rules Team (2022-05-26)
If I play Phoebe while my opponent has a Dunsparce with "Mysterious Nest" Ability in play, do my Pokemon VMAX's attacks calculate Weakness if applicable or not?
The term "any effects" does not include effects that alter Weakness and Resistance. So Phoebe does not allow you to ignore Mysterious Nest's effect.
If my opponent has a Galarian Cursola V's "Gnawing Aura" Ability in play, if I use Zarude V's "Jungle Rising" attack and attach any energy cards to one of my Benched Pokemon, do I place the damage counters for "Gnawing Aura" first and then heal, or vice versa?
The player using Jungle Rising gets to choose which order to place damage first and then heal, or heal first and then place the damage counters for "Gnawing Aura".
When you attach "Rainbow Energy" from your hand to Skiploom with the "Solar Evolution" Ability, do you place the damage counter onto it before or after evolving to Jumpluff?
The owner of Skiploom can choose the order of the effects. They can choose to place the damage counter from Rainbow Energy before evolving; however, if they choose to use Solar Evolution first the effect of Rainbow Energy is ignored because Jumpluff is not the same Pokemon the energy was attached to.
While the opponent's Galarian Cursola V's "Gnawing Aura" Ability is working, if you attach an energy from your hand to your Skiploom with the "Solar Evolution" Ability, do you place the 3 damage counters onto it before or after evolving to Jumpluff?
The owner of Skiploom can choose the order of the effects. They can choose to place the damage counters from Gnawing Aura before evolving; however, if they choose to use Solar Evolution first the effect of Gnawing Aura is ignored because Jumpluff is not the same Pokemon the energy was attached to.
If Mew VMAX uses its "Max Miracle" attack against the opponent's Fusion Strike Pokemon while the opponent has an Oricorio with the "Lesson in Zeal" Ability in play, does "Max Miracle's" damage get reduced or not?
The damage reduction of Lesson in Zeal is considered an "effect on the Pokemon". Max Miracle ignores ANY effect on the opponent's Active Pokemon, so therefore Max Miracle would be able to overcome the effect of Lesson In Zeal.
If I have a confused or poisoned Genesect V with 2 Fusion Strike Energy attached, and my opponent has a Cradily with the "Swaying Strangle" Ability in play, would I be able to Retreat after I have discarded the 2 Fusion Strike Energy cards as the cost, or would I no longer be able to Retreat?
Since you began the Retreat process while Swaying Strangle was prevented by the Fusion Strike Energy, you get to complete the action and Retreat even after discarding the 2 Fusion Strike Energy cards. The behavior is also similar with Flygon's "Labyrinth of Sand" ability or Snorlax's "Block" ability.
My Arceus V is active and I have Dunsparce with "Mysterious Nest" Ability on my bench. If my opponent uses Spritomb's "Ticking Terror" attack does Arceus V now have {D} weakness, or does "Mysterious Nest" keep it with no weakness?
The Ticking Terror attack would switch Arceus V's weakness to {D}, but then Dunsparce's Mysterious Nest would change Arceus V back to no weakness. However, since Ticking Terror says "Until the end of your next turn..." Arceus V would become weak to {D} if Dunsparce were to leave play or have its Mysterious Nest ability shut off.