I wish Gourgeist's SpA wasn't as terrible. I'd really like to run an Assault vest set with Giga Drain, but with that special attack...
Uninvested Assault Vest Gourgeist reaches 279 SpD, and its uninvested defense is 282. An adamant max attack Gourgeist with assault vest has stats of:
374/ 328/ 282/ x/ 279/ 144
That's definitely a solid tank, with great typing. Obviously EV's can be moved around to target specific threats, or survive certain attacks. With resistances to the ever so common types Water, Electric, Fighting, Ground, and to a lesser extent normal, this thing can find quite an easy time switching in. With assault vest limiting it to attack moves, it really would like a usable giga drain for recovery, but it can still come in on things like starmie or rotom-w and easily do away with them.