By which we mean to say: emulators for the PC and for the GP32 generally use the same ROM formats. There are exceptions: GenesisMu chokes on BIN format Mega Drive/Genesis roms. And the old GBA emulators didn't support roms over 4 megabytes in size.
However, these exceptions are rare and you should almost always be able to simply copy the ROMs from your PC to your GP32 and run them. Sometimes, even save game files can be shared!