Poliwrath 98% (RS/DP)
with Rock Smash / Dynamic Punch. 1600 CP.
worth Powerup? is he a good fighter?
Answers
It's listed as A rank as attacker, is sligthly behind B/DP, but in terms of usability, movesets with 2 moves of the same type are more desireable (In my opinion), because while you migth loose a little bit of damage in raw DPS of the moveset, you will gain a little more damage because you'll get SE damage in both moves in the matchups where you want SE damage.
Now the caveat to this is that the damage output is not so different between both movesets (Ex. one is rated A and one is rated C or lower).
Edit, forgot to point out that this is just for prestieging purposes, for attacking, Machamp and Heracross are head and shoulders above good old polywrath. He's not bad, there's just better options out there. In case you don't have a better figting type, then sure, power him up.