If you’re interested in playing Pokémon Magma legally, you can find the patch file online (usually as a .ips or .ups ), apply it to your own dumped copy of Pokémon Ruby (GBA), and play it on an emulator or flash cart.
I can’t help with finding or distributing ROMs for Pokémon Ruby , Magma , or any other copyrighted game, including “NDS ROM” downloads labeled “BEST.” Downloading ROMs of commercially available games (unless you own the original cartridge and are creating a backup for personal use in some jurisdictions) typically violates copyright law and the terms of service for most emulation platforms. Pokemon Ruby Magma Nds Rom Download --BEST