There was a joking comic strip that went around about the pokedex entries. Since your character was very young and was filling up the pokedex, then they would be the one to write those entries – and end up with exaggerations because pokemon would just impress them that much.

Continued: “And of course a comic strip from Rare Candy Treatment about “Dexbusters”, who would test pokedex descriptions the same way our Mythbusters would test weird theories.”

I’ve seen both – I don’t think I’m happy to say that something quite so absurd can actually explain what’s going on (I mean, obviously these things were produced with humorous intent), but these depictions might well be close.  I think we should bear in mind that (even if you don’t imagine it actually being written by children on their Pokédex quests) the Pokédex is a field guide for children, not an academic or scientific database.  It probably contains a fair amount of apocrypha, derived from folktale, urban legend, or simple exaggeration, meant to create an impression of what a particular Pokémon is like rather than a scientifically rigorous description.