Things You'll Need
Instructions
Connect the Game Boy Advance with a game connection cable to another Game Boy Advance. Insert the "FireRed" or "LeafGreen" cartridge into one slot and the "Ruby" cartridge into the other. Turn on both systems.
Travel to the Route 114 area in the "Ruby" game file. This Route is located to the west of Fallarbor Town. Search in the tall grass of this area to encounter Zangoose. Lower his hit points by attacking with your Pokémon; throw a Poké Ball to catch him.
Return to Fallarbor town. Enter the nearest Pokécenter and talk to the person at the desk on the second floor to enter the trade center. Do this on both game systems. Select "Zangoose" from the file on "Ruby" to trade it into "FireRed" or "LeafGreen." Zangoose will be added to the game's Pokédex.