* No Online Multiplayer: Pokemon Ruby is a Game Boy Advance game, and the console doesn't have online capabilities.
* Limited Multiplayer Options: The only multiplayer option available in Pokemon Ruby is "Link Cable" battles, which allows two players to battle each other directly using a physical Game Boy Advance Link Cable.
To play a single battle with a friend, you would need to:
1. Have two Game Boy Advance consoles: Each player needs their own console and a copy of Pokemon Ruby.
2. Obtain a Game Boy Advance Link Cable: These cables are sold separately and connect the two consoles together.
3. Find a location to battle: Both players must be in the same location to use the link cable.
Alternatively, you could:
* Play against each other in a different Pokemon game: Some later Pokemon games (like Diamond, Pearl, and Platinum) have wireless options for battling friends.
* Use an emulator: You can use a Game Boy Advance emulator on your computer to play Pokemon Ruby and battle each other virtually.