I've only found two instances where that has happened: The Twelve and Blood of Apocalypse. Three if you count Age of Apocalypse but that was an alternate reality.

It seems that he was mostly a villian for spin-off X-series like X-Factor and Cable/X-Force.

Yep mostly alt realities and futures, and then some additional cameos.

Apocalypse turned into a cataclysmic symbol of a threat more than being one himself. A writer with imagination can turn it into a future to be X-classic.

They also battled him during the "X-cutioners Song" crossover.

You can add X-Cutioner's Song, and three more battles if you count the O5 in the original X-Factor.

@adamtrmm: Like how Nightcrawler made a joke out of him twice.

@masterofevil:

Such a terrible portrayal, I'm actually glad Lemire didn't bring the "real" Apoc in for that story.

He can still be fixed!

@invain:

I think that is the X-factor he meant.

@adamtrmm: Yeah, I know, but with it bring the o5 it is essentially the X-Men.

@adamtrmm: People have been saying that since Blood of Apocalypse. The age of Marvel villains is over. Now nonsense plot twists and pop culture references rule the Marvel Universe.

Not enough.

@invain: Technically they weren't X-Men at the time. Just former members that made their own team.

@masterofevil:

They also thrash the A-listers for some reason, without actually covering new areas, but they call it change still. Go figure.