Believe it or not! I just went through the full argument of Ninja ban!
Did you realize how some where just making excuse of how 'unpredictable' ninja is. Tbh I didn't expect a council full of pvpers to say it lmao. PvP is about predicting. Why do you want to make pvp a kids game. If ninja is banned for that than ban every poke that can run a wide movepoll lol. Anyway, some said it has wide movepoll to cover everything. Bro, The 4 move syndrome duh! You unbanned Metagross for that, why not Greninja.
Let's look over to other facts. Some argued that ninja can learn spikes which is bad since its offensive and can pressure most defoggers. That's again no reason to ban a mon for. They argued that it kills rotom/zapdos/tentacreul and other stuff that can get rid of hazard. What about the other way around? Greninja can't Ohko any of them even with super effective moves, in return if they just predict an incoming ninja and just volt swtich, sludge wave or use any attack at all, they kill it or almost kill it.
I saw someone arguing to ban spikes with ninja if they think its broken with that. Now all way along the chat people where complaining about the Greninja spikes set, when the dude provided a solution, he was ignored lmao. Someone told its better to fully ban or not ban at all, that's it.
Greninja has been a problem to the only team IK is Stall. The only thing I would consider to be broken about is setting up spikes against incoming walls. How is that a bad thing? Just play it out right, most defoggers (as said above) pressure ninja bcs of their typing and ninja won't swtich in to them! Defog than! Create situation to defog. That's what pvp is about! Playing smartly. Not about banning a mon bcs it can learn alot of different moves and you are lazy to scratch your head and think about which moves it might carry.
One more thing to consider, They say that it's hard to learn what set greninja is and in process of learn your mon dies. If most of us answer these honestly, we know it's not possible 80% of times or more. Greninja even with protean and orb cant pick 0hkos on traditional walls in PRO (top 25 most used pokemon list) like Chansey (doesn't even do 50% with low kick and it can softboil back) Clefable ( Gunk shot isn't a Ohko, just switch when u see) Ferrothron (hp fire/low kick doesn't Ohko) easy leech seed back or swtich and many others. All these walls can easy click their heal moves since they are slower than ninja, heal off most of the dmg dealt and you already know the ninja set (from dmg dealt sp.atkr/atkr and most moves from the same).
Thanks for Your Opinion and Links you provided.