Two Pokédexes, two diplomas: 156 Pokémon for the Unova one, 649 for the National one. In Black and White, many of the older Pokémon cannot be found in the wild. Here is the method to collect them all, version by version.
The diplomas are handed out by the game director, on the 21st floor of the GAME FREAK building in Castelia City. The first rewards a complete Unova Pokédex, the second the National Pokédex.
For the Unova Pokédex, the event Mythical Pokémon (Victini, Keldeo, Meloetta, Genesect) are not required for the diploma. For the rest, you will need to combine catching, evolution, trading and transferring.
