Deoxys was a pretty popular Pokemon in the Hoenn days, back then it was basically compared to Mewtwo as the new ultimate strong legendary.
Sadly Movie 7 wasn't great, it's Ranger special in Battle Frontier was meh, and its DP filler ep was just another Piplup-DP era episode. So I don't really care to see it again.
Trip has already been seen possessing six pokes. I'm sure once we see them again, they'll all be in their final forms or close to it. This would imply him having in the League Serperior, Unfezant (unknown gender), male Jellicent, Chandelure, Vanilluxe, and Conkeldurr. It is possible he changed one of these pokes, but I think we'll see them anyway, even if it's in a battle with one of the other characters like what Paul did. Since Trip has no beef with anyone else (save perhaps settling the score with Bianca), I find this unlikely.
Step into the Fairy circle