There are 202 including jirachi and deoxys.
You have to catch 151 pokemon to complete the pokedex.
You get the Pokedex after choosing your starter Pokemon in Prof. Birch's lab.
catch all Pokemon
I believe there's 202 in the Hoenn pokedex specifically, and 386 in the national.
It is grimer
The original Pokedex is given to the player by Professor Birch. After the Pokemon Ruby trades with LeafGreen or FireRed the National Pokedex will be unlocked.
beat the hoenn pokedex and go to prof.birch
you can check the pokedex, it is in fiery path.... and many caves! Just check the pokedex, it's quicker.
you don't need to catch them just see all the Pokemon in the hoenn pokedex
http://pokemondb.net/pokedex/national
On www.serebii.net, click on pokedex and search the Pokemon you want to see. All Pokemon need a different amount of steps. With the pokedex you can see that. You need to know what Pokemon it is!
www.serebii.net/pokedex-rs/