Of course, you only need to worry about memory size for Pokémon Ultra Sun and Pokémon Ultra Moon if you are grabbing either title digitally.
Additionally, a brand new trailer for both Pokémon Ultra Sun and Pokémon Ultra Moon was revealed last month during Nintendo’s Fall Direct, highlighting some of the main differences between versions and what people pre-ordering can expect. Both Pokémon Ultra Sun and Pokémon Ultra Moon release on November 17, 2017 exclusively for Nintendo 3DS.
According to the Amazon Japan listing for Pokémon Ultra Sun and Pokémon Ultra Moon, either game will require 3.6 GB of memory.
For those trying to keep there eyes on (or clear space) for their Nintendo 3DS, the 3.6 GB translates to 29500 blocks.