Question

Where do I find the tm for wil-o-wisp in Pokemon y?

Answer 1

TM 61(Will-o-wisp) is found in route 14.
Just follow this video to get it: http://www.youtube.com/watch?v=bdKGAv-cE20
(BTW, you will need HM01 Cut)

Answer 2

Route 14, south of Fairy Girl Imogen. Requires cut to obtain.

Source.