Is Azelf, Uxie, Mesprit and Phione Pixies?

Is Azelf, Uxie, Mesprit and if possibly Phione is one are Pixie mythical

Also is Phione a mythical Pokemon since earleir last month it was proved it’s not a legendary and it’s not a Ultra Beast it’s either Mythical or Normal Pokemo

Nope. They have nothing to do with the plot.

Phione probably isn’t one since it doesn’t have to do with the plot either and the only way to get it in this game is also breeding Manaphy. Also I’m pretty sure it’s just a normal poke technically.

what plot i just need to know if they are Pixie Mythicals

Pixies aren’t exactly a real category of Pokémon. The term is used mainly in Insurgence for the plot, so if a Pokémon has nothing to do with the plot, it most likely is not a pixie. By the way, the lake trio are legendaries, so they’re disqualified to be in the category.