The moveset itself is good enough for defending purposes yes.
However you will be spending a lot of dust and candies for this, and that extra +300cp won't do much defending the gym to be honest.
I prefer to use my dust and candies for attacking pokemons - when talking about powering up past lvl 30, cause they are the ones you really use.
So this is my opinion, but I don't think it's worth it.