When it comes to facing nero, its not the 4c's that i worry about: It's those damn pets: the 3 versions of the deer, the crow, that snake with the big mouth. they are all brutal set ups to lead to punishment if you're not careful.
While i cant say that i am the best when it comes to beating Nero, i do have an idea of what to look out for.
1: The deer: There are 3 versions: 1 hit- the deer jumps and disappears, 2 hit- the deer walks out then does 2 dashing attacks, ex (3 hit)- same as the 2 hit but the deer dashes three times.
-Between the 2 hit and the 3 hit versions, there is a small opening between each deer dash where you are vulnerable to a throw if you are on planted on the ground.
-careful when attacking between each deer dash, that guy luvs to counter your attempts, setting you up for a 4c combo
2: that snake: the once i fear the most is the one that eats you (dunno the version). Careful when trying to counter a snake attempt. Any bit of hit recovery that the snake catches you will result with you in being eaten.
3: The Crows: 1 shoots the crow like a quick projectile, another sets up a crow for a diagonal dash attack. The ex version sets up a barrage of crows for a diagonal dash attack. Beware of the possible set ups of the ex version. Trying to block a ex crow set up could make you get thrown. At the same token, trying to attack when the ex crows are out will result in a barrage of crows from going at you if even the slightest hitbox of your sprite is touching the path of the crows. Trying to jump block the crows could also set you up for an unblockable.
This is all i can think up being on the receiving end of Nero.