20.
Tinkaton's hammer is about 220 lbs! Yet she can swing it as if it were a feather in the wind, and her phys. atk. is only at a base 75. I have a theory that tinkaton's phys. atk. is low only because she is does not know how to use her strength. It is like she relies solely on her hammer but does not put much power into it. Maybe she expects it to do all the work? Either way she is bulky, and that tells me that Tinkaton is a strong pokemon. Also because her hidden ability is pickpocket you can combine that with fling shenanigans. Have Tinkaton hold no item, use any contact move to steal opponent's item, throw it back with fling, repeat.