An old Regice question...

[Blue Wave]

I´m 100% sure I´ve seen the answer somewhere, but cannot remember it for my life.

Can you discard 2 cards with Regice even if the Defending Pokémon is an Evolved Pokémon and then realise Regi Move has no effect, or does it have to be an Unevolved Pokémon?

[PokePop]

The Compendium is a great place to check for official rulings.
You can go to the bottom of the document to click on the name of a card/power/attack and get taken right to rulings on it.
Like... this:

http://compendium.pokegym.net/compendium-lvx.html#285