Screech

Until the end of your next turn, if an attack damages the Defending Pokemon (after applying Weakness and Resistance), that attack does 20 more damage to the Defending Pokemon.

Poison Bite10

If this attack damages the Defending Pokemon, the Defending Pokemon is now Poisoned and you remove a number of damage counters from Golbat equal to half that damage (rounded up to the nearest 10). If Golbat has fewer damage counters than that, remove all of them. Either way, the Defending Pokemon is now Poisoned.