You just play the game usually when you beat the Eliet 4 you have seen all the pokemon.
You have to see all the Pokemon in the Sinnoh Pokedex.
catch all the Pokemon or use an action replay
you see all Pokemon then click the pokedex then see the Pokemon you want then click area on the pokedex hoped i didnt helped
you cant but it will fill out your pokedex
use actionreplay cheat for pokedex
just battle and capture as many different types of wild Pokemon as you can, for me i had to battle a certain trainer because my pokedex was missing one so search on the enternet to find a certain Pokemon you might be missing
Catch all the Pokemon.
check marriland.com's pokedex it shows you all the Pokemon if you type the in the Pokemon you want to see.
you can't but you can trade Pokemon at the pal park
you have to see almost all the Pokemon in the normal pokedex then professor.rowan gives you a national pokedex and then you unlock a place behind sandgem city and its called pal park and you get to pick witch Pokemon you want to migrate
By seeing all the Pokemon in sinnoh and going to rowen's lab.
collect all the Pokemon in the national pokedex