I would name that Chinchou "Capt. Hook" because Lanturn are based lightly on anglerfish, which are in turn named because they are similar to anglers, meaning those fishermen who use fish hooks, hence the nickname
As such, the nickname for Dratini could be "Belle" derived from Tinker Bell, a character from the movie Peter Pan in which Captain Hook appears
Finally, I would name that Slowpoke "Philippa" because Philippe, Belle's horse in The Beauty and the Beast seems athletic and runs away with danger, which is ironic in my mind because I think a slowpoke would rather stay and face the danger, albeit I can't imagine how.