If my Pokémon uses Agility and get heads then on my opponent's next turn he benches his Pokémon, does that [Ed. Note: Agility's effect] end? If that Pokémon was Knocked Out, would Agility still be on the next Pokémon that he sends up?

Since the Agility Attack references Rapidash, only Benching or Evolving him ends the effect. Also since it only refers to Rapidash it would still be in effect if the other player benched.

Relevant cards