Can I use Ninetales' "Nine Temptations" Ability if my opponent has no benched Pokemon?
Yes, you can discard 2 {R} Energy cards from your hand, and that's it.
Source: Team Up FAQ (2019-01-18), TPCi Rules Team (2019-01-31)

Relevant cards

Note: All applicable cards may not be listed below.
SM9_16
SM9_16