Trouble with a last slot Poke

[Enderpan]

This is just really short, and requires just a short anwser, based on preference.

What would be considered the most important or the most useful type of pokemon out of this list:

Hazer
Spiker
Cleric

Also, if you wish to know, the pokes i would use in each circumstance would be Crobat, Cacturne, and Vileplume respectively. If you want to know the other pokes I have, here: Absol, Milotic, Gardervoir, Metagross, Salamence.

Thanks

[Number1ChanseyFan]

Out of those three choices, I would go with either a Hazing Crobat or the Aromatherapy Vileplume. Spikes are nice, but you can do fine without a spiker. I think that a Hazing Crobat will work well for you.

Crobat

Jolly Personality, EVs: 252 Attack, 252 Speed, 6 HP
Haze
Shadow Ball
Aerial Ace
Sludge Bomb
@Liechi Berry/Leftovers.