You can now download the Planet Monsters ROM for the Gameboy Advance. It’s exclusively available on romzie.com for free. All you need to play is an emulator.
Other GBA games such as Wario Land Advance (C) and 2 In 1 - Yu-Gi-Oh! - Destiny Board Traveler & Yu-Gi-Oh! - Dungeon Dice Monsters are free to download and play on any desktop, PC, mobile device, and tablet from Romzie games.