As long as Hitmontop is an Evolved Pokémon, is your Active Pokémon, and is damaged by an opponent's attack (even if Hitmontop is Knocked Out), put 2 damage counters on the Attacking Pokémon.
Upward Kick
If the Defending Pokémon already has at least 2 damage counters on it, this attack does 20 damage plus 30 more damage.
