While it is technically possible, the data of each trainer will be located in a different offset within the game. Some of them may be clustered together, but overall it would likely be more effort than remaking trainers manually.
My suggestion is to use "Hopeless Trainer Editor". It has an import/export feature. You could export all your trainers, then import them into the new rom. I think that would be the simplest solution.
Hey, I had a question: Do you know if it's possible to move the trainers pokemon data from one fire red game to another? I ran into an odd glitch that I can't fix and don't want to do ALL the trainers over again. I'm using the Fire Red 1020 Base from Pokefreak, and wanted to transfer it to another clean copy of the game. Is that possible?