well, even regarding my last post here, some other (not really serious) idea concerning something like a 'crossover':
I Just the day before yesterday I came to watch AVP 2 in cinema. Lacks a bit of story actaully and is really gory, but in a more brutal way than the other movies, so overall, I liked AVP 1 much better.
Anyway, it remined me of something I've read in a DS9 set after Series - Novel: There the Jem'Hadar named Taran'atar (sent by Odo to protect Kira) always does some kind of training at the Holosuites (like Worf did in TNG) und replays battles the Jem'Hadar have fought. Under the many intimitating enemies there is a species described which actually is meant to be (in my opinion) the 'Xenomorphs' aka 'Aliens'.
Also in one of the Gateway-Novels this Jem'Hadar fights against a Hirogen (was very good to read) a it was mentioed that these two species had had run-ins before.
Therefore I suggest a 'Hirogen vs. Xenomorph' the Star Trek-Version of AVP.
Alternatively there could be also some kind of Mini-Series always with to battle-hardened species fighting each other, good candiates would be:
- Hirogen vs. Species 8472 (as seen in VOY)
- Jem'Hadar vs. Arcturian MACOS (during Dominion War it has been mentioned that the Arcturian Clones were the main Ground Troops)
- Kzinti vs. Xindi Reptilian
- Rigelian Kaylar (from EV) vs. Quch'ha (the mutated Klingons from ENT)
- Capellans vs. ?