If I don't have any cards in my hand, can I use my Mr. Mime's "Trick Reveal" Poke-POWER to look at my opponent's hand?
Yes. You still have a hand, it just has no cards in it. Show your (empty) hand when your opponent shows their hand.
Source: Call of Legends FAQ (2011-02-10), PUI Rules Team (2011-02-10)

Relevant cards

Note: All applicable cards may not be listed below.
COL1_29