Megaman doesn't really need Connie's to shut down greninja, or anyone really. Sure, if you try to play mega like greninja, and compare them directly in a rush down and combos sense, greninja is a better rush down character. Megaman isn't rush down though, he zones all day with projectiles and "get out of my face" moves like up smash, dtilt, leaf shield, throws, and melee range nairs.
Sure a full charge shuriken is strong, but it's also really telegraphed. Mega has plenty of time to interrupt or reposition.
It's a pretty decently balanced match up, I'd say it's probably 50/50 and really comes down to how well mega zones vs how well greninja can infiltrate.
Technically Greninja isn't a rushdown character either, his approaches aren't that great and he isn't necessarily going to be rushing anyone down with his bad frame data, quite a few of his moves are too slow to come out. He's bait and punish, not necessarily rushdown, mind you. These two characters play a bit more similarly than you might think, actually: In most of his matchups, Greninja actually wants YOU to approach him with Shurikens and then punish you with big damage the moment you make a mistake, and while fully charged shurikens are telegraphed they still eat through every move but Leaf Shield and provide a huge reward on hit and baits with shield, and it is an option to counter poke (if not necessarily counter-camp) against your projectiles if he jumps back while charging it. And while his approaches are bad, theyre still an option and he still has the mobility to get around lemons. Aside from his bad frame data, his weakness is is extremely bad OoS game: no UpB, Nair, or Usmash Out of Shield, and he's got a terrible standing grab with 14 frames of startup. But considering Mega Man's equally laggy moveset and high land lag on his aerials, I don't really think he can do much to exploit this besides using Fullhop MB or maybe Bair, and this weaknes ain't as much of an issue for him as it usually is in his other matchup. The reason I keep comparing damage output & combos so much is because it's (imo) his greatest weakness: Sure you can zone opponents out for days and condition them with them with lemons, MBs, Crash Bomber, and Leaf Shield; but all these generally deal little to no damage and your kill moves kinda suck, you're not really going to do much damage to them in neutral or when you get an advantage. And while you're neutral is great, your opponents are going to get in eventually, and a good amount of them are going to deal far more damage and catch up easily with the damage you dealt to them from neutral, and while those "get off me" moves you mentioned are options, none of them are really safe and you're gonna eat quite some damage if you get combo'd (especially when you're a heavy fast faller). This is no problem against someone like Ness or Luigi since they lack mobility and struggle too much in neutral for oppurtunities to use their power, but faster guys like Greninja and Falcon don't. You might be able to keep them out for awhile and thhtheir approach game is below average, but they still have ways to navigate around your zoning and its not as effective against them as it is with other characters, and once tey finally start punishing you they're likely going to get a lead and its too hard to get back in the game.
I agree that its a mostly even MU, but I personally still rate it 55:45 in favor of the Ninja. Just like the Falcon MU: You might win the neutral, but once he gets an advantage you have to put in a lot of work to keep up with him damage-wise and his kill moves outclass yours, and he's got his ways to get around your zoning: one of the faster run speeds, 2nd highest jump in the game complete with good airspeed (he can even get around projectiles just by jumping over them), and a Nair that outprioritizes lemons and combos into many moves on hit. Sometimes, especially when he has the lead, it could be argued he might not even need to approach because he's got his water shurikens that help his already slippery mobility. If Greninja kills you first and gets a lead, its gonna be pretty hard to get back in the game, which is pretty likely since MM needs pretty hard reads for most of his kills or use MB > Utilt and doesn't have as many kill setups. If you manage to kill Greninja first though and you get a lead, you can say the same thing about him, really hard for him to turn the tides and get a comeback if he doesn't get a lead since he's a bit reliant on rage for kills (I still say its better than anything Mega Man can do tho) and he doesn't exactly enjoy it when he has to approach, and i not for this Greninja would probably be just as bad if not worse than the Falcon MU imo. As of this patch, I think it got even better for him: He now has less startup on his shurikens (imo the most painful nerf he got from 1.0.4, totally unnecessary change) so it becomes easier for him to use it and its a real significant buff for him, and Dthrow now true combos into Fair at around 125% I believe, which gives a decent tool to make comebacks should he be killed first.
On a side note, if you ever think about using Rush to get out of Greninja's Uair combos, you'll regret it
BIG time
