Ruling opponents hand?

[daviduk2000]

is the number of cards in your opponents hand public knowledge?

i.e if im thinking of using copycat. and ask before using it. does my opponenet have to tell me how many he has in his hand?

or do i have to wait until i play the card then find out?

same with attacks that do more damage if you hands bigger/ same size as your opponents?

 

[King Arceus]

The number of cards in a players hand is public knowledge. What cards are actually in their hand is not. If you ask them how many cards they have in their hand they are required to respond truthfully.~Mark