Hacking gba cheat loader?

[ComicMaster148]

I was wondering if I could use an r4 card to load cheats on my gba game cartigde, sort of like a gba game shark? Is it possible

 

[FAST6191]

Real cart? No. Best you can do there is flash a hacked save back to it. There is no real path to either boot a GBA cart as an "emulated" affair* or go the other way and have DS mode homebrew touch the GBA ROM/memory in some way.

If you have a flash cart and are running a GBA ROM but your method does not have cheats then there is
https://gbatemp.net/threads/gba-auto-trainer-maker-gbaatm.99334/

*technically you could dump a GBA cart, run it in one of the enhanced flash cart emulators (so the supercard DSTWO family really) and then flash the save back. There are very very limited GBA emulators on the DS but they are not good. Far better in that case to dump the save (and the game if you like) and run that on a PC emulator or something before flashing back the save.