Just got a little chuckle out of the fact that all of the bi-weekly summer books had events going on except for the mutant comics. Events? Storylines? We're the X-books! We don't need any of that! And it's true. Sales on the X-books would have dwarfed anything else there, except for Spider-Man.

To be clear, it's not like the X-books didn't have events. Excalibur was coming off of the Cross-Time Caper during this bi-weekly period, and X-Men were building up to the X-Tinction Agenda crossover with New Mutants and X-Factor. But to get the kids to buy twice as many Captain America comics during the summer, they needed a special story, whereas the X-books just barreled on through.

And Quasar to represent the Avengers?

I guess Cap is pulling double duty. But at least Quasar appears in the Crossing Line. Havok does not appear at all in X-Men #263-268 (or any of the other books listed).

The Purple Punisher Plot!

Wolverine's book did have a story in issue 27-30- the Lazarus Project. Although calling it a story is generous since a quarter century later I'm still not sure what the Master Form was supposed to be.
The annoying thing about Excalibur 24-29 is that half of those issues were fill-ins. If the writer can't do the bi-weekly schedule, then you really shouldn't be going biweekly in the first place.