To get the National Pokedex, you must have seen all Pokemon from the regional Sinnoh Pokedex after beating the Elite Four and Champion. After doing that, go to Sandgem Town and talk to Professor Rowan in his lab and you will get the National Pokedex.
That pokemon is Azumarill in pokemon platinum in the national pokedex
No.
You do need the national pokedex for the Pokemon modifier. the Pokemon modifier uses the national pokedex numbes. you can not use the sinno pokedex.
In the National Pokedex in Pokemon Platinum Mawile is Pokemon 303.
The first Pokemon in the national pokedex is a bulbasaur
nothing
all of them in the regional pokedex
493
on national pokedex its umbreon
Pokemon Platinum has two different Pokedexes: the Sinnoh dex and the National Pokedex. In the Sinnoh dex, #152 is Rotom. In the National Pokedex, it's Chikorita.
in the sinnoh pokedex dusclops, in national pokedex aipom
In Pokemon Diamond and Pearl you need the National Pokedex to get Magnemite. In Pokemon Platinum you don't need the National Pokedex to get Magnemite.