Red Dead Redemption 2: Ultimate Edition

Does anyone know if the trainer for Red Dead Redemption 2 will work also with the Ultimate Edition?

It should. I believe it’s the same game.

As far as I know, all the ultimate edition does is adds more cosmetic items, plus a new bank you can rob.
Most of the bonuses Ultimate Edition gives are for online gameplay, which trainers will not work on anyway.

If you’re looking for more than a few cosmetics or online bonuses, then I’d suggest avoiding the ultimate edition.