As long as Plusle is your Active Pokemon, whenever your other Active Pokemon, if any, attacks, you may use Cheer On after the first attack(you still need the necessary Energy to use Cheer On).You can't use Cheer On more than once in this way even if your other Active Pokemon has the Chain of Events Poke-Body.

• Cheer On

  Remove 1 damage counter from each of your Pokemon (including Plusle).

• Extra Circuit

  Choose 1 of your opponent's Pokemon. This attack does 20 damage to that Pokemon. If you choose Pokemon-ex, this attack does 40 damage instead.(Don't apply Weakness and Resistance for Benched Pokemon.)