Mega Gengar ex - Darkness - HP350
Stage 2 - Evolves from Haunter

Ability: Shadow Hiding
If 1 of your [D] Pokemon is Knocked Out by damage from your opponent's Pokemon ex, your opponent takes 1 less Prize card. This effect does not stack.

[D][D] Void Gale: 230 damage. Move 1 Energy from this Pokemon to 1 of your Benched Pokemon.

Mega Evolution ex rule: When your Mega Evolution Pokemon ex is Knocked Out, your opponent takes 3 Prize cards.

Weakness: Fighting (x2)
Resistance: none
Retreat: 2

Too bad that Gardevoir attacks with single prizers and damage manipulation.