Competitive Guide: Chainite

[shademonkey]

Lately I've been looking a lot into the Assault Vest item, what makes a good user, and on the contrary which mons should not be considered to use it. If you're like me and didn't already know what traits make an efficient Assault Vest holder, or if you're simply curious, here's a short list of resources you can read : 
Out Of Style: Why Assault Vest Can't Be Slapped on Just Anything
Biting the Bullet: Assault Vest
What Pokemon(s) can abuse the assault vest effectively?

What needs to be remembered is that good Assault Vest users should already have tanking capabilities.
They should have a way to heal off some of the damage they take, either with draining moves like Giga Drain, or with abilities like Regenerator, Poison Heal, Blood Lust, the situational Water/Volt Absorb. If they can't do that, they should have key resistances that allow them safe switch-ins; or prove effective at threatening out the mons they come into.
Users should be able to fire off powerful blows, since attacking is the only they're allowed to do.
Opportunity cost : is Assault Vest really worth using over another item? Isn't the pokemon too reliant on its support movepool?

I know the item isn't in the game yet, I really look forward to the final update that implements the missing items left. In the meantime, a little speculation can't hurt, can it? As I was scrolling down the dex for potential candidates, I noticed that Chainite seemingly possessed some of the qualities required.

• On the offensive side, Chainite has everything it needs to perform well : excellent Attack BS, great offensive coverage with access to Ghost and Fighting moves, stab Knock Off, coverage moves in Earthquake and Gyro Ball, and priority in Shadow Sneak.
  
• On the defensive side, Chainite is... average. Its Ghost/Dark typing grants it only one weakness to Fairy, but it still takes neutral damage from every other types bar Poison and immunities. Its defenses aren't terribly bad per se, but Chainite can't rely on them be considered a tank. Drain Punch can serve as recovery. Curse Body isn't too reliable but could prove useful in disabling an opponent's move, effectively forcing it to switch out.
  
• Opportunity cost : The more I think about it, the less I think Chainite could be efficient in the role of a defensive check. Since I'm not too sure if, despite its interesting typing, its defenses are enough to make it tank enough hits to come out on the field repeatedly; I wonder if it would not rather use an attack-boosting item and stick to something it is better at, ie Trap-killing. You guys tell me what you think
  

Other pokémon I'm looking into for potential future Assault Vest users :
Majungold, Herolune, Tubareel, Haagross, Baariette, S51-A
Tell me what you think!