Things You'll Need
Instructions
Raise a Fire-type Pokemon like Torchic and Numel to at least Level 25. Teach it "Flamethrower" or "Ember." You will use this Pokemon to weaken Tropius, since Fire-type moves are effective when used against it. Make sure you have a few dozen Ultra Balls in your "Bag."
Go to Route 119, which is directly west of Fortree City. Walk in the long grass and flee from the Oddish, Zigzagoon, Linoone and Kecleon. Don't flee from any Tropius you encounter. Tropius will appear about 9 percent of the time.
Use Fire-type moves on the Tropius to make it easier to catch. Be careful not to defeat the Tropius, or you won't be able to catch it. Go to your bag and select "Ultra Ball" from the Pokeballs section. Continue throwing Ultra Balls at the Tropius until it stays inside.
Insert "Pokemon FireRed" into one Game Boy Advance and "Pokemon Sapphire" or "Pokemon Ruby" into another. Connect the two Game Boy Advances with the GBA link cable. Power on both GBAs. Go to a Pokemon Center in "Pokemon FireRed" and "Pokemon Sapphire" or "Pokemon Ruby."
Go upstairs and talk to the receptionist behind the far right counter in "Pokemon FireRed" to go to the Cable Club. Speak to the lady behind the middle counter in "Pokemon Sapphire" or "Pokemon Ruby." Offer any Pokemon in "Pokemon FireRed" for the Tropius. Select the Tropius in "Pokemon Sapphire" and "Pokemon Ruby." Press "Trade" in both games to trade the Pokemon.