Other known variants
x2Mysterious Nest
Pokémon in play (both yours and your opponent's) have no Weakness.
RolloutWhen it sees a person, it digs a hole with its tail to make its escape. If you happen to find one, consider yourself lucky.
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 
or do they have no Weakness at all?
The Star Cipher attack would switch your opponent's Pokemon's weakness to , but then Dunsparce's Mysterious Nest would change all colorless Pokemon to no weakness.
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.
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 
weakness, or does "Mysterious Nest" keep it with no weakness?
The Ticking Terror attack would switch Arceus V's weakness to , 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 if Dunsparce were to leave play or have its Mysterious Nest ability shut off.
