The Masterball is a rare item in "Pokemon FireRed" that allows you to catch any Pokemon on the first try without battling it. This is especially useful for Pokemon that tend to flee the battle on the first turn. You only get one Masterball per game. Thankfully, you can use a GameShark device to input a code that will make any Pokeball have a 100 per cent capture rate, thus making it act exactly like a Masterball.
Insert "Pokemon FireRed" into the GameShark. Push the GameShark device, with the "Pokemon FireRed" cartridge already connected, into the cartridge slot of your Game Boy Advance.
Enter the code, "896FC3BFB7FE 738971087308" at the GameShark code screen. Press the start button to begin the game.
Select your save file and battle any wild Pokemon. The Pokemon will be automatically caught when you use any Pokeball.
This does not work on Pokemon belonging to other trainers.