The £8million summer arrival from Sunderland has scored three goals in his last three games across all competitions after an injury-interrupted start to his Potters career.
Pulis still believes the Trinidad and Tobago international has plenty more to offer.
"Kenwyne's got all the tools to be an outstanding player for this club," said Pulis.
"Three goals in his last three games have helped his confidence, but I firmly believe there is a lot more to come from the lad.
"We still think he can get fitter, he can be a lot sharper, and if he manages to do that, then he will be a real handful for defenders.
"Having said that, he's worked really hard to overcome the injury setback and he has worked well with the other players too, so we're delighted with the impact he has already made. 'He is a fantastic signing for this club."