(From what other bugs I've seen on the tracker recently, it seems as if these new guys are just full of bugs...)
I've found an issue in which Overqwil and Basculegion fail to register in the Pokédex. Here's everything that I know:
I used a Pokémon Editor to give myself Basculegion and Overqwil. Usually, doing so registers any previously unobtained Pokémon.
Opening the Pokédex while pointing at either Pokémon does not register them as seen.
Both new Pokémon appear to have incomplete data in the .lang files (They're both missing their Pokédex entries and are out of alphabetical order, based on what I saw.)
The new Pokémon will still spawn (proven with the /wiki command) and be used in battle, so it seems to be Pokédex-related only.