You should watch:

The Enemy

This was episode number 7 of season 3.

The following characters appeared in this episode:

Captain Jean-Luc Picard
Chief Miles O'Brien
Centurion Bochra
Counselor Deanna Troi
Commander Wiliam T Riker
Commander Tomalak
Doctor Beverly Crusher
Lieutenant Worf
Lt Commander Data
Lt Commander Geordi La Forge
Patahk
Wesley Crusher