Oh 35:65 seems fair enough. I'd have went for 40:60 but evidence does suggest 35:65.
I just see '-3' matchups being ZSS vs Rob, Rosalina vs Ness and I dont think sheik greninja is as bad as them two matchups.
In my opinion I see Captain Falcon/Rob/Ike to have -2 matchups vs Sheik and I think Greninja's matchup with sheik is no less bad than theirs.
The common thing all 4 characters vs sheik is that sheik completely dominates their gameplan but they kill way earlier than Sheik does, preventing it from being --3.
ZSS vs ROB and Rosalina vs. Ness are -3 matchups on the basis of the advantage/disadvantage states, so it's more clearly a -3. You see Ness offstage getting insta-gimped by Rosalina's down-b and you're like "wow, that's stupid, -3." Natural reaction.
Greninja vs. Sheik is -3 (probably it's only -2 but hey, I'm not one to argue numbers, just offering perspective) not because of disadvantage but because of neutral, so the loss is a lot subtler.
Forget the theory for a second, and forget real matches that you've seen. Put yourself in the Greninja's shoes (webbed feet?). You've just started playing game 1 of a set vs. a top-ranked Sheik. Stage is like, idk, Smashville or Town and City or FD, whatever. Match starts, Sheik begins charging Needles. What do you do?
A) Throw Shrukens. Needles are transcendent, so this won't work.
B) Approach using a short hop aerial or tomahawk (using dashgrab because standing grab is lol). You're going to get f-aired for your trouble, Greninja's fastest aerial is his b-air iirc, and Sheik's not scared of your empty hop.
C) Approach using shield. Hello, bad OOS options, meet Sheik's ridiculously rewarding throw combos. Your shield is going to get jab1, jab2d, followed by a grab.
D) Use your mobility to weave in and out of Sheik's range until you can get a dash attack or dash grab going, all the while blocking needles on reaction. Only, hey, Sheik's weaving is even better, with the best options out of dash in the game, so somehow your higher mobility specs don't actually matter, and you just get grabbed a whole heck of a lot.
E) SD twice and pick another character.
When E actually looks just as promising as A, B, C, and D, you've got a pretty grim matchup on your hands.
God, why do I not main Sheik?