ok fine i'll answer
Trevenant
Pros:
Harvest and frisk can be powerful ability's
Harvest works well with Charizard-Y because of drought
Ingrain, Leech seed plus whatever berry bonus you choose is a good stall strategy
W-o-W is a move that can and will cripple powerful enemy's
Confuse ray (no explanation needed)
Cons:
Taunt will destroy him
Substitute will destroy him
Watch out for houndoom
Gourgeist (Super size)
Pros:
Good Defense which your team needs
W-o-W to cripple opponents
Trick or treat to gain an offensive bonus
Leech Seed
Destiny Bond and Explosion
Scary face to deal with it's low speed
Cons:
Taunt
Substitute
Bad special defense
Terrible Speed
Overall choose trevenaut he's better at stalling which your team needs and 2 dark types? maybe add a normal type