Where do you get the master ball in fire-red?

You can't get a Master Ball in FireRed version. It's a special item that was only available in Generation II games (Gold, Silver, and Crystal).

While there are many guides that mention getting a Master Ball in FireRed, these are usually outdated or incorrect. The only way to get a Master Ball in FireRed is through glitches, which can be risky and may corrupt your save file.

It's best to focus on playing the game normally and using other Poke Balls to catch Pokemon!