It's decent, but not that great. Subpunch does a decent job of beating things that normally switch into Poliwrath, like Grumpig, Roselia (which Ice Punch hits harder), and Clefairy. However, outside of luring things, special is usually better. Specs isn't that great either, it's really easy to take advantage of when it's locked into a move and doesn't like the lack of Leftovers. The order of sets in terms of how good they are in my opinion is Rain Dance > Special Tank > Subpunch > Specs > Resttalk.