Pokemon Red: Fire Single Game Monotype Challenge

You may not use Legendary Pokémon, even if they are of your type.

No trading Pokémon from other games, unless you are doing so for an evolution that requires it.

When starting your journey in each game, you will have to play the game using just your starter Pokémon. Then, once you gain access to the first available Pokémon of your type, continue from then on with only that type. You can use your starter to help with training these Pokémon, but cease using it in gym battles at this point. In the Kanto games, you also must catch the first Pokémon of your type before cutting the bush east of Cerulean City.

You can use HM slaves of different types; just don't use them in battles. The exception to this rule is with Psychic teams in the Hoenn games. Due to the fact that the Abra and Ralts families literally have no means of combating Poochyena and their fellow Dark-Types at the start of the game, the HM slaves can be used to help them out.

You may only use Pokémon that share a type. Dual Types are allowed, however. So, if you're doing a Flying monotype challenge, you may use the Water/Flying type Gyarados. If you are doing a Water monotype challenge, you may also use the Water/Flying type Gyarados. You can use Pokemon not of your type if and only if they will evolve into a Pokemon of your type at some point, though you should evolve them at the first chance you get. Also, if you are doing a Normal monotype challenge, you may not use an Eevee and evolve it into a Jolteon, because it is no longer the correct type.

If you cannot trade for whatever reason, and you're using one of the types mentioned in the last two points, hacking a single low-level Pokémon of your type into your game will be allowed. You would also be permitted to evolve Pokémon in this manner, if they require trading to do so. These are the only instances where hacking will be tolerated.

The challenge for each game is completed once the Elite Four is beaten for the first time(except in the second generation where it ends when you defeat Red, and in the fifth generation where it ends when you defeat the Elite Four for the second time). At said point, you can then begin with the following game.