Well, you can't trade them in either. Also, the child who uploaded that video was able to obtain the old amber and revive Aerodactyl in under 3 minutes, it is not too long. And...you will be able to use Aerodactyl for eight gyms and the final battle with Red after the Elite Four. Not to mention, you can still use Lickitung and Qwilfish much earlier in the game. The challenge would not be a challenge if you were able to just hack or trade half of your team in. However, in-game trades are permissible, although it does not pertain to the Pokemon assigned to you.