So I'm assuming that when Oricorio copies a dance move, it uses the move against the same opponent as the original attacker...but I wanted to make sure I was right.
We could summarize these tests overall in the following way: If a Pokemon uses a dance move on some target, then the Dancer Pokemon is forced to use new its dance move on that original dance move user. If an ally to Dancer uses a dance move on some opposing target, then the Dancer Pokemon is forced to use its new dance move on that original target.
source I would trust Smogon's research threads more than Showdown! replays.
The move used by dancer targets a random opponent. source
It targets the Pokemon that used the move.