Initial clarification: I’m not requesting the ability to make shiny troops look not-shiny in BATTLES (although that would be a nice option, I guess), just in the TROOP INFO menu.
When your troops become shiny, there is no in-game way to see what they used to look like. It would be nice to have an option, maybe in the menu below, to toggle shiny visibility on the troop so you can see the differences better and take screenshots of the non-shiny variant if desired.
As soon as a troop becomes shiny, I instantly forget what it looked like before it was shiny 