See all 150 Pokémon and beat the elite 4, then talk to Proffesser Rowan.
484-500
Unlike in other games you just have to see the Pokemon not catch them but when professor oak gives you the natinal pokedex you have to catch the Pokemon
you can foud ivsaur in Pokemon diamon in route 225 for your natinal pokedex
The first Pokemon in the national pokedex is a bulbasaur
get a bubasour
Mew three is an exclusive to chaos black
by seeing all 150 sinnoh Pokemon including palkia.
get 60 in your pokedex and go to oaks lab
The Pokemon Mothim is number 47 in the pokedex(will be different in the natinal pokedex.Hope it helped:)
The Pokemon 47th in the pokedex on Pearl, is Mothim
Number 25 on the pokedex in Pokemon pearl is BUDEW the grass & poison type Pokemon.
All the Pokemon from the Diamond and Pearl Sinnoh Dex, plus 60 others. These include, Ralts (and evolutions), Houndour (and evolutions), and Giratina. if you are not sure like i am \ was then check out serabii.net for more info