You know...I'm sure that this thread isn't surprising in the slightest. If we're going to find out whether or not Mega Kangaskhan is truly threatening, then I say we look at a different part of a guideline we used with Mega Gengar. Remember the Support Clause? How about the Offense Clause? How does that go?
"A Pokémon is uber if, in common battle conditions, it is capable of sweeping through a significant portion of teams in the metagame with little effort."
Let's focus on this for a little bit. What do we know about Mega Kangaskhan? We know that her ability, Parental Bond, gives her the power of a Choice Band, the ability to break Subs and Sashes, she has 200 BP Seismic Tosses, WISH (how, how HOW and WHY!?), powerful and reliable moves like Return, Earthquake, Crunch, boosting moves that are exploited through Parental Bond (I'm looking at you, Power-Up Punch), decent bulk that is most definitely nothing to scoff at considering that nobody doubted Hydreigon's bulk in Gen V, and the ability to plow through even some prepared teams! It takes VERY specific Pokemon to stop her and, even then, they can't always stop her. Rocky Helmet sets grew more popular because of her, Sableye is used more often...not only could one argue that an entire metagame is being centralized around one Pokemon...which is ALWAYS a bad thing, it completely fills in what the Offensive Characteristic for an Uber Pokemon is. It CAN sweep through a significant portion of teams. It not only CAN, but it WILL if you don't pack one or two Pokemon SPECIFICALLY for her. If you really want to go far, one could possibly implement a similar system used for Sneasel's Little Cup Ban with three questions:
1. Is Mega Kangaskhan Broken?
I would argue that, because of the above reasons, Mega Kangaskhan is truly broken; giving even Uber Pokemon a run for their money is a startling suspition of its power in OU.
2. Is Mega Kangaskhan making OU not fun?
Though OU hasn't truly been made, I'm assuming Pokebank battling. Goodness, Mega Kangaskhan isn't making anything fun. To be honest, over centralizing makes battling boring. Teams become far too similar, nobody is allowed to experiment in fears of this Pokemon, the same Pokemon are always used and they become predictible for your opponent AND you when facing them. With that said, Mega Kangaskhan is definitely making battling not fun.
3) Is a combination of 1 and 2 deterring individuals from playing OU?
For me, it made me take a break from battling. I'm not sure about everyone else, but I'm sure that if it doesn't deter others from playing, it will magnetically pull them into a centralized metagame where you either use Mega Momma or prepare for it (I've seen entire teams dedicated to stopping Mega Kangaskhan...). Mega Kangaskhan should be quickbanned. If we held a Suspect Test, it'd most likely end up the same way anyways. We all know the strengths, we all know her ability to walk over her supposed Checks and Counters, and we all know that she has made playstyles more popular only for stopping her. I'm sure the proof is clear.