Well two things. When shiny, the branches stay the same and the base of the Corsola is darker. Next, this is a hard thing to notice but during raids it is hard to see if the Pokémon is shiny because of the glare. In fact, I encountered a Shiny Charizard in a raid and I didn’t know it was shiny till the raid ended because of the glare. They need to fix that. Hope this helps you.