#255
professor oak gives it to you
133
#94 I believe
spiritomb in the sinnoh dex lickitung in the national dex
National Numbers are the PokéDex numbers that each Pokémon in the National Dex is given. Each Pokémon has a different number assigned to it depending on if you are reading the regional Dex for each region or the National Dex. Like for example in Sinnoh's regional PokéDex, Turtwig is #001 however in the National Dex, Bulbasaur is #001 is Bulbasaur. Victini is registered in Unova's regional Dex as #000 however in the National Dex, it is registered as #494.
Check your pokedex. You should be able to switch to the national Dex. If not, then you have not obtained it yet.
you get all the Pokemon
Yes, you can trade Pokémon between Pokémon Platinum and Pokémon HeartGold regardless of whether you have the National Dex in both games or not. All Pokémon can be traded into both games without the National Dex however if they're not included in Platinum's Sinnoh Dex or HeartGold's Johto Dex then they won't be recorded in the Dex until you get the National Dex.
Piplup's National Dex number is 393.
professor oak gives it to you
Wednesday, after you get the national dex
the Pokemon for national dex number 124 is jynx and for sinnoh dex number 124 the Pokemon is azurill.
Pokewalker Course- Quite Cave (100000w + National Dex to unlock.)
Not possible EDIT THE BDK WAY:get national dex and talk to Mr.Pokemon
Yes, under the National Dex as Pokemon #383.
after getting the national dex go to mr pokemons house and he will gkve it to you
#96 in the Sinnoh dex #440 in he National dex