Shiny circles shiny pokémon !

Question

While I'm senading out two shiny pokémon (in a double battle)some shiny (light blue ) circles appear between the two pokémon .why ?is this happening in other gens ?

Answer 1

This is the notification that the Pokemon are Shiny. If the other player is somewhat stupid and doesn't know the colors of the Pokemon you sent out, that tells them that they are Shiny. In a single battle, the star-circle appears in front of the Pokemon. In triples, the circle appears in front of the middle, same with Rotation. So, it is just a notification!
Hope I helped ;)