Because Smogon works with
tiering systems (OU, UU, RU, NU, Ubers, Monotype etc.) the next thing you need to know is what metagame do you want to play. I suppose you have OU in mind?
Then you can check what are the main threats of this metagame (using a tool such as
Pikalytics) and start planning a team that can deal with those threats. In OU that would be mons such as: Landorus-T, Magearna, Tapu Koko, Kartana, Chansey etc.
Greninja-Ash has a much higher usage than Protean Greninja in OU (at the time of writting Greninja-Ash has 16.80% and Greninja 11.06% according to Pikalytics).
From the moveset you mentioned it looks like you want it to be an all-out special attacker, but in that case wouldn't Greninja-Ash be better for that role? Otherwise this Offensive Protean Greninja would need Choice Specs to be viable, but in that case the unpredictability aspect of the Protean ability is totally lost... It would be nice if Protean Greninja could deceive your opponent and fake Battle Bond, but that seems impossible after the first turn since your Protean ability will be revealed after it makes a move.
I am not saying that it is impossible to use Protean Greninja in OU and that you should go for Greninja-Ash, only that maybe an all-out special attacker set is not the best choice for the former mon. Greninja is an awesome pivot or hazard setter. Even in an offensive role it is temporarily a far superior mon because until Greninja-Ash transforms it has a useless ability!
