When I'm playing a Pokémon game and I look up a Pokémon to check which moves it will learn at what level, I get the moveset of the newest generation (USUM/gen 7 at the moment).
Let's say I'm playing ORAS (gen 6). Then I'll have to click the 6 next to In other generations first before showing me the correct gen, then click the ORAS tab to get the correct moveset.
Could there be some sort of setting (via a cookie?) that determines the moveset shown in the Pokémon Pokédex/detail view?