Weirdly all the preview footage shows the same stuff. I guess TPCi provided the b-roll so they'd have something to talk over.
Only exception I've found is this guy, who got to show their actual gameplay of Great Marsh and walking around Veilstone to show off the customization
They added a trainer with a girafarig near the meteors, for whatever reason.
Wasn't the only other NPC addition (aside from the gracedia lady) we've seen a Hiker with a Gastly? Kind of interesting?
So have any boss teams that are relevant for Platinum dex been seen?
No
However, honestly, at this point I firmly believe they'll all be 1:1
Every trainer we've seen thus far, and every wild Pokemon that has not been in the underground, has been equally 1:1 with DP specifically.