Everything Pokémon: Pokémon Facts Book 1

Pokedex Science #6

Kadabra:
"It happened one morning - a boy with extrasensory powers awoke in bed transformed into Kadabra."

This means two things:
1. All Abras are horribly-deformed human children, and when it evolves into Kadabra, it has gone to sleep and awoken a monster.
2. Every single Kadabra is a human child, who has somehow switched places with Abra, who have taken over the child's human bodies.

And - perhaps most terrifying of all - unless the child/Kadabra is traded, he will never evolve and get that additional spoon.