Ecter

Ecter is a Ghost Type specialist and the gym leader of Hallow Town. When you defeat him you receive the Scare Badge, as well as the ability to use Defog outside of battle. You also receive Destiny Bond and Shadow Sneak, and you can use Shadow Sneak outside of battle.

Team
Misdreavus/Mismagius

Shuppet/Banette

Duskull/Dusclops/Dusknoir

Uhgar/Braenz

Smirage/Villusion/Endeception

Gastly/Haunter/Gengar

Gym
The gym is a giant graveyard, with trainers hiding behind the gravestones, and you have to find the 6 correct gravestones to fight Ecter.