This Pokemon FireRed and LeafGreen trick will give you practically every Pokemon without glitches

Pokemon FireRed and LeafGreen they are infamous for the many glitches they have caused over the years, whether it was something players could use to their advantage or something that was always detrimental. There are many examples. One of them is how Pokemon FireRed and LeafGreenThe mail duplication bug allowed players to cheat any item they wanted. Another is that roaming Legendary Beasts can interrupt the game and never appear again after using Roar, and while that is fixed in the current version of the Switch games, the other bug about their IV always being 0 isn't. Still, there are ways to take advantage of what the game has to offer without needing glitches.

One such thing is RNG manipulation, which allows you to get exactly as many Pokemon as you want from the list of possible seeds if you do the trick correctly. Not to be confused with ACE, which instead generates Pokemon out of thin air and even allows you to create NPCs to trade with to get evolutions exclusively for solo trade. Pokemon FireRed and LeafGreenHowever, manipulating the RNG is not easy and you have to be very precise to really get something out of it. But if you succeed, you will be able to get practically any Pokemon you want.

Shiny Charizard, Psyduck and Sandslash in Pokemon FireRed and LeafGreen

The best strategy for catching Pokemon FireRed and LeafGreen is unfortunately an exclusive version

Shiny hunting in Pokemon FireRed and LeafGreen is always at full odds, but the best trick you can use is exclusive to one version.

How to find your secret ID in Pokemon FireRed and LeafGreen

The way RNG manipulation works is to use software like PokeFinder to check the Pokemon you have to determine its SID (Secret ID), which is then used to determine what kind of Pokemon you can find, and then use a toolkit to get those exact Pokemon. The essence of finding your SID is as follows:

Catch a Pokemon, check its gender, nature and stats and track them.
Level up a Pokemon either through Rare Candy or by battling wild Pokemon and Trainers and watch all the EVs it gains in the process. Note any other changes to the Pokemon's stats per level.
After a few levels, use a Gen 3 IV calculator like this one and enter all the correct information about the Pokemon, such as species, nature, level, current stats, and any EVs gained.
Repeat the process above until you've narrowed down the Pokemon's IV to a set of specific numbers. When you determine your Pokemon's IV, use PokeFinder, go to Gen 3 Tools and click on IV for PID.
Insert the Pokemon's IV next to its character and your trainer ID (found on the trainer card in Pokemon FireRed and LeafGreen). This will determine your SID, which you can then use to find the Pokemon you want.

Drag your weapons to fill the grid

Easy to medium hard

How Pokémon FireRed and LeafGreen's RNG manipulation works

Finding your secret ID is the only way to make RNG manipulation work. After that, the first step is to go to a website called Ten Lines and search for specific Pokemon. You can use the filters to choose whether the Pokemon should be shiny, have a specific gender, have a specific nature, or have a given IV range. There are two main things to keep in mind here:

RNG manipulation does not generate Pokemon, but rather uses existing Pokemon seeds to allow you to catch the exact Pokemon if you time the process correctly.
The seeds are limited and tested by community members, so there may be other options that you don't see.

You can then use a program called EonTimer to help you determine when to press A on the splash screen, save file screen, and finally on your static Pokemon (eg. Pokemon FireRed and LeafGreen appetizers, Eevee in Celadon City, etc.). It also works for fishing, via Rock Smash, wild Pokemon via Sweet Scent, event Pokemon and Legendaries. However, you have to perform three perfectly timed button presses in a row, which is not easy. However, if you miss your goal, Ten Lines and EonTimer have ways to help you calibrate the process, meaning you enter data to adjust the timers accordingly until you finally hit your goal.

While this method can be tricky and intimidating at first, it allows you to get pretty much any Pokemon in the game without cheating or using glitches, and that includes rare pets like shiny Mewtwo, Legendary Birds, and more. Assuming you find your SID with a random trigger, you can reset the game to a moment before choosing the trigger, if you haven't saved in the meantime, and then continue manipulating the RNG to get a shiny starter. Pokemon FireRed and LeafGreen without spending dozens of hours in Oak's lab.