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



x2
Spore BallYour opponent's Active Pokémon is now Asleep.
Powdery UppercutYou can use this attack only if this Pokémon used Spore Ball during your last turn.
It scatters poisonous spores and throws powerful punches while its foe is hampered by inhaled spores.
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.