In the first game, you have to catch all legendaries and battle every trainer you encounter
150 Pokemon
I'm not sure about catch but in the Sinoh dex you can see 150 Pokemon
150
you have to see 150 Pokemon then talk to professor oak..
you need to see 210, you need to see 150 for Pokemon diamond and pearl
you need 150 Pokemon to get the national pokedex
150 then talk to Professor Rowen.
150 hope i helped :) Actually there are 151 pokemon in the Sinnoh Pokedex but you only have to see 150 to get the National Pokedex.
By Trading.
you have to see all the Pokemon through 150 then talk to professor oak
for diamond and pearl there are 150 Pokemon u need to see . in plat nium u neeed to see 210 Pokemon.
you have to get the national dex when you see all 150 Pokemon orif you play platinum you will have to see all 210 Pokemon