This page and this page on Serebii give you all the details you need on the move tutors in both B/W and B/W 2 respectively, since you didn't specify which, but I am going to assume you require that for B/W 2, what with all the new Pokemon from other regions you can catch, and hoe B/W are now sort of out dated.
I do no think you need a Move Tutor. To evolve Pilowswine into a Mamoswine, you need it to learn Ancient Power, a move Piloswine learns at Level 1.
Thus, you need the Move Relearner
The Move Relearner can be found in Mistralton City, in the house next to the Pokemon Center.
Keep in mind you do need a Heart Stone in exchange of Ancient Power, though.
Source: Personal Experience