Poliwrath's Fighting Moveset

Poliwrath is certainly viable in those roles, but his attack stat is fairly poor and Machamp etc. will do it much better. The only real niche I've found with him is against Fireblast Tyranitar, but even then his DPS is far from ideal and it's not a good choice if trying to short-man it.

By all means, use Poliwrath if you like him and he'll perform well enough, but I think maxing him would be a waste of Stardust.

If you have the stardust to burn i'm an advocate for doing things to stave off boredom in this game. Do it and name him Punchywrath

Poliwrath with RS/DP excels against Lapras due to resisting all its moves while dealing SE damage.

How many TMs (and dust) do you have?

(I remember using Exeggutor with Cn/So, Flareon with FS/OH and Gyarados with Bi/HP against Blisseys under the old gym system.)

Don't waste Stardust because of Niantic's ignorance to the absolutly broken, tired, and ridiculous battle/gym system.
Just save stardust for now.

Instead, email them that you want a better battle system:
https://support.pokemongo.nianticlabs.com/hc/en-us/articles/115008306667

I used to use fighting Poliwraths against Tyranitar, before I had an army of C/DP Machamps, and before Hariyama, Blaziken, and Breloom were released. The Poliwraths were solid for 3-manning T-tar, and I kind of like the tough little guy, but they are somewhat outclassed these days. They're fun to use when the opportunity arises, though, and fun to show off in gyms occasionally.

Instead of maxing him, maybe consider taking him up to L35 or so. It takes 88K stardust and 118 candies to go from L35 to L40, and you get minimal real improvement for that cost. But if the candies and dust are no problem, and you want a trophy Poliwrath, why not?

I have a L38 poliwrath that I’ll use occasionally against TTars for variety. Machamp is still far better, but Poli can hold her own and looks cool.