Unlike the previous games, Pokédex 3D included numerous updates that added or unlocked features which previously required you to reach certain milestones to obtain. These are all accessed via the update function of the game.

Update #1 - Pause Button

Japanese Date: October 3rd 2011
American Date: October 3rd 2011
European Date: October 3rd 2011

Details
The first update involves having a Pause Button added to each Pokémon. Typically, these are obtained by having the Pokémon sent to you by a friend, but this update will automatically unlock it for all Pokémon you have obtained up to this point. This update can be downloaded again and again.

Update #2 - Augmented Reality Features

Japanese Date: October 3rd 2011
American Date: October 3rd 2011
European Date: October 3rd 2011

Details
The second update unlocked all the various features of the Augmented Reality viewer that previously needed you to scan the various Pokémon's AR Markers into the game and register them as stickers. This varied from number of Pokémon on screen at once, to the scale feature and so on. Click here for details

Update #3 - Hidden Pokémon

Japanese Date: June 1st 2012
American Date: ??
European Date: ??

Details
The third update unlocks the six Pokémon that cannot be normally obtained in the game; Victini, Cobalion, Terrakion, Virizion, Reshiram and Zekron. These Pokémon previously were only accessible by scanning their AR Markers.

Update #4 - Exclusive Pokémon

Japanese Date: June 1st 2012
American Date: ??
European Date: ??

Details
The final update unlocks the various previously Savefile Exclusive Pokémon as well as those that previously needed you to scan the AR Marker to give them a chance to appear via SpotPass.