>>17103709...because it's best used as a special attacker with a hard hitting U-Turn (read mixed), or a pure special attacker because it has a better special move pool. This is not an opinion, it's a fact. I've used physical, mixed, and pure special and I know this to be true.
Now, on the off chance that you want to do physical froggy (even though there are much better physical attackers) it's pretty simple. Don't use Power-Up Punch, it's ass on everything but Mega Momma and some Ass Vest sets. What you're going to do is use U-Turn, Return, then any of these two: Water Shuriken, Waterfall, Aerial Ace, Night Slash, Shadow Sneak, or Rock Slide.
Fling and Acrobatics is viable, but not recommended for the physical set as he doesn't have the HP to tank a hit if the Fling isn't don't lethal damage (read: it won't).
The only advantage to using physical Greninja is that if Talonflame isn't using a speed enhancing nature with 252 speed, and Greninja IS using a speed enhancing nature with 252 speed, Greninja can almost always OHKO Talonflame with Water Shuriken. And yes faggots, Water Shuriken is better than Aqua Jet (this is not an opinion, it's a fact).
tl;dr - don't use it as pure physical, go mixed or special, I wasted a lot of time trying garbage sets
