You can Import/Export the Trainer/Pokemon Texture with the Ohnana "BCH Texture Replacer" (Ohana Rebirth/Tools/bch Texture replacer...) i hope i can help you ^ ^
I know to change the overworld Texture (Post here: https://gbatemp.net/threads/pokemon-sun-and-moon-garc-files.445401/page-28#post-7568522) But the Battle Texture i can't change sorry
Yea is right but when you export the .png how you can import the .png File? (This was my first problem too)
For Example i used the a\0\8\3 dec_2465.bin (that is the Aether Fundation Outside Texture)
1. Unpack this with Pk3Ds (!!!NOT WITH OHANA REBIRTH!!!)
Pk3Ds Create a dec_2465_BG Folder...
Caller -"Everytime I start a Pc game on my S24, playing on a external monitor, someone calls or texts me, n it kicks me out of the game." Customer Support - Click (hangs up)
I found it funny cause many many years ago, had a roommate in college that did this same dumbass branding of the school logo, but it didn't look anything like it after it healed. Just looked like a birthmark.