I have beaten the Elite 4 in Saphire, the Professor comes and looks at the Pokedex but doesn't offer the National Dex, I have ALL the pokemon u can get in Saphire and even traded from Ruby/Emerald ( haven't beaten these yet, only got what I needed 2 fill Saphire) so I technically have ALL Pokemon except the event ones. After credits and save I go 2 the lab but the Professor isn't there anymore. Went 2 DEVON corp 2 c if they offered it but no.
>In Pokémon Ruby and Sapphire, the Pokédex is upgraded to National Mode after the game trades with Pokémon FireRed, LeafGreen, or Emerald. Trading with Pokémon Colosseum or Pokémon XD will not unlock National Mode.
A trade unlocks them. If you traded with Emerald, then there is something wrong with the game. Try trading with FireRed and LeafGreen.