Does Sharpedo EX's "Hunt" attack do 30 damage if the opponent cannot switch their Active Pokemon to the Bench or if the Bench is empty?
If you cannot switch the opponent's Pokemon there is no "new Active Pokemon" to be damaged, so no damage is done.
Source: TPCi Rules Team (2015-02-05)

Relevant cards

Note: All applicable cards may not be listed below.
XY5_152
XY5_91