You'll need to put a female or a male (Better with the same species) in the Day Care and wait for a certain amount of steps and then talk to the Day Care guy. You can also use Ditto, which will breed with any Pokemon, except Legendaries and genderless Pokemon (Such as; Beldum, Metang, Metagross, etc.).
Yanma can't be found in Pokemon FireRed or Pokemon LeafGreen; it is strictly a fourth generation Pokemon.
it's in pokemon leafgreen
Staryu is a water type Pokemon. In Pokemon FireRed, it is possible to find lots of Staryus in the Seafoam Islands.
Celebi cannot be found in Pokemon FireRed. The only way to get Celebi in Pokemon FireRed is receiving it from an event distribution. These events are sadly no longer supported for Pokemon FireRed.
It's not possible to find Sudowoodo in Pokemon FireRed. You will need to trade for one from a Pokemon Emerald game-save.
migrate it from Pokemon FireRed
You cannot find Piloswine in the wild on Pokemon FireRed. You can find it's pre-evolved form Swinub in Icefall Cave on Floe Island in the Sevii Islands of Pokemon FireRed.
Shroomish is not available to be caught in the wild in Pokemon FireRed, it must be traded from Ruby or Sapphire.
You can't find it in Pokemon fire red
Chikorita cannot be caught in Pokemon FireRed. However, you can catch a Bayleef in Pokemon Colosseum, transfer it into FireRed, and breed it to get a Chikorita egg.
Fossils cannot be created in Pokemon FireRed, there is a finite number of them to find.
The only way to obtain Magmar in Pokemon FireRed is to trade it from LeafGreen.