For Cedric Juniper, can the opponent look at any face up cards around them to figure out the height of a Pokemon. Can he/she look at an open binder nearby?
You could look at other Pokemon that are in play but not at a binder. Just on the field, in your hand, or in the Discard Pile for either player.
Source: TPCi Rules Team (2013-11-21)

Relevant cards

Note: All applicable cards may not be listed below.
BW11_110