Yes you evolve it at night with a razor claw and you can get one at the battle frontier
How Does Evolve Sneasel In Pokemon Soul Silver?
I believe it needs to hold razor claw and has to level up at night. (Not sure)
Make it hold a razor claw and level it up at night.
You get a razor claw and level it up at night. Sadly the razor claw can not be obtained in SS or HG