Day 1 player, caught my first shundo and its hard to tell it is even shiny

I was doing party play with a buddy and the reward screen popped right as I was trying to join a raid. I rushed to catch it and didn't really look at it as I was complaining to my friend that I might miss the raid. The "new PokeDex entry" appeared and I was confused since I already a Tandemaus but I didn't think about it any more as I quickly jumped into the raid. Hours later I was clearing out my Pokemon and saw that the Tandemaus was shiny. I evolved it, checked its stats, and was surprised that it was a shundo!