Lucky dex, why the max is not 951
A full Pokédex has 951 Pokémon as of this writing, after Squawkabilly was released. But that is not the same as how many Lucky Pokémon you can actually have, your "Lucky dex".
Lucky Pokémon come only from trades. Almost all mythicals cannot be traded, so they can never become Lucky. The real max for your Lucky dex is therefore 951 minus the number of Pokémon that cannot be traded.
There are 18:
- Celebi
- Darkrai
- Deoxys
- Diancie
- Eternatus
- Genesect
- Hoopa
- Jirachi
- Keldeo
- Marshadow
- Meloetta
- Mew
- Shaymin
- Victini
- Volcanion
- Zarude
- Zeraora
- Zygarde
Zygarde and Eternatus are actually Legendary, not mythical, but they are still in the club for some reason.
That gives a realistic max of 951 minus 18, which is 933 Lucky Pokémon.