Can I use Vanilluxe's "Slippery Soles" Ability to make my opponent switch Pokemon if I don't have any Benched Pokemon?
No you may not. Slippery Soles requires you to switch your Active Pokemon with one of your Benched Pokemon first.
Source: Next Destinies FAQ (2012-02-09), TPCi Rules Team (2012-02-09)

Relevant cards

Note: All applicable cards may not be listed below.
BW4_33