Abilities » Mysterious Nest | Attacks » Star Cipher
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)
Abilities » Mysterious Nest | Trainers » Phoebe
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.
Source: TPCi Rules Team (2022-05-05)
Abilities » Mysterious Nest | Attacks » Ticking Terror
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.
Source: TPCi Rules Team (2022-03-31)