The following list of pokemon are catchable or obtainable in Pokemon FireRed:
Ekans
Arbok
Oddish
Gloom
Vileplume
Psyduck
Golduck
Growlithe
Arcanine
Shellder
Cloyster
Scyther
Electabuzz
Bellossom
Wooper
Quagsire
Murkrow
Qwilfish
Scizor
Delibird
Skarmory
Elekid
Deoxys (Attack Forme)*
*Deoxys is an Event pokemon that can only be obtained with cheat codes and it has three forms, Attack, Defense, and Speed. The attack forme is exclusive to Firered.
There are too many Pokemon to list here, please refer to the related link below. Keep in mind that version exclusive Pokemon are listed in a separate section and some of the Legendaries listed can only be caught if you received a specific event item.
There is no official Pokemon game that has all Pokemon catchable in it, which means you'll have to trade and transfer Pokemon from other games to get all the Pokemon. However, some fan-made hacks do have all the Pokemon catchable in them.
In Pokemon firered you can't, but in Pokemon leafgreen you can get it then trade it to Pokemon firered.
If you are talking about the 2 mascot Pokemon then you have the following: Reshiram - The "Vast" Pokemon. Reshiram is Fire/Dragon type and is only catchable in Pokemon Black. Zekrom - The "Deep" Pokemon. Zekrom is Electric/Dragon type and is only catchable in Pokemon White.
trade it from red,blue, or yellowMewtwo is not catchable in the wild in Pokemon Crystal.
Unfortunately, Mew is not a catchable Pokemon in FireRed. It is impossible to catch it without a Cheating Device. Sorry, The interwebs fooled me, too.
They are not catchable on any Pokemon game,however you can trade to get the starter Pokemon squirtle and charmander on Pokemon Leafgreen/Firered.
*Mew is not catchable in Pokemon x and y, but you can get him online from wondertrades and such. Mewtwo however, is catchable and you can find him in the cave in pokemon village.
You can't get pikachu in Pokemon colosseum you can see it but that's all, if you want pikachu you would have to trade one from firered, leafgreen, ruby, sapphire or emerald.
There are too many Pokemon to list here, please refer to the related link below. Keep in mind that version exclusive Pokemon are listed in a separate section and some of the Legendaries listed can only be caught if you received a specific event item.
sudowoodo and smeargle
There is no official Pokemon game that has all Pokemon catchable in it, which means you'll have to trade and transfer Pokemon from other games to get all the Pokemon. However, some fan-made hacks do have all the Pokemon catchable in them.
Of course in certain games its catchable like in gold, silver and crystal, some games get it via event like firered and leafgreen. You can also get a ho-oh in Pokemon colosseum.
The catchable legendaries are the following: Articuno, Zapdos, Moltres, Raikou/Suicune/Entei *depends on your starter pokemon*, Mewtwo.
In Pokemon firered you can't, but in Pokemon leafgreen you can get it then trade it to Pokemon firered.
There is no Pokemon convention in firered.
If you are talking about the 2 mascot Pokemon then you have the following: Reshiram - The "Vast" Pokemon. Reshiram is Fire/Dragon type and is only catchable in Pokemon Black. Zekrom - The "Deep" Pokemon. Zekrom is Electric/Dragon type and is only catchable in Pokemon White.