Here's a fun little question to think about.

[Darkstorm16]

Does Ash keep his old Pokedex in like say his top left hand drawer or something in his desk if he got one? Or does he just give his old pokedex and Prof. Oak just grab it from him and upgrades it. It just makes you wonder.

 

[Rex Kamex]

The second one. We see this a lot.

 

[game_mayhem]

Oak upgrades it, because first oak gathers the old data and then inputs the new data on the newer version of the pokedex.

 

[S.Suikun]

Considering how each Pokedex is an entirely different model, no doubt he just puts his old ones away somewhere.

 

[Hikozaru390]

I think the old ones are given to Oak, recycled, and made into new Pokédexes.

 

[penngrade6]

I think oakjust takes the old dex and upgrades it.

 

[TheBuddyBud]

no, oak gives the outdated pokedexes to poor pokemon trainers as charity

 

[Lupin]

The Prof simply takes the old ones away and upgrades it.

 

[Francesc]

Oak upgrades it all the time