Some questions about the mystery challenge

In a mystery challenge (where you can’t see the other pokemon) if you have already caught a pokemon and registered it to the pokedex, if you see it again will it be hidden still or show what it actually is.
Also, if you encounter a shiny can you see the shiny sparkles or will you only see it after you catch it?

Just curious.

you see the particles and pretty the pokeball indicating you caught it before shows up