.ek6 is Generation 6 Pokémon Save File
Key Features: .EK6 File Extension
What is an .EK6 file?
Pokémon save file used by 6th generation Pokémon games for the Nintendo 3DS platform, such as Omega Ruby and Alpha Sapphire; stores information about a Pokémon, including its nickname, friendship, language, ball type, contests stats, and latest handler.
EK6 files can be opened, edited, and created by the PKHeX utility, which is a Generation 6 equivalent of PokeGen. You can use PKHeX to generate .EKX files through PKHeX by creating a EK6 file and renaming the extension to "ekx."