If Breloom gets sent to the Bench after using its "Spore Ball" attack, can it still use its "Powdery Uppercut" attack on the next turn?
Yes, because it is a game state check and not an attack effect.
Powdery UppercutSpore Ball




×2
Spore BallYour opponent's Active Pokémon is now Asleep.

Champignon's SwingFlip a coin. If heads, this attack does 80 more damage.
Pokémon ex rule
When your Pokémon ex is Knocked Out, your opponent takes 2 Prize cards.
If Breloom gets sent to the Bench after using its "Spore Ball" attack, can it still use its "Powdery Uppercut" attack on the next turn?
Yes, because it is a game state check and not an attack effect.