They all have strengths and weaknesses & they all benefit certain line ups separately.

Water Main is the only main that can reliably sustain over a large portion of rounds- no other main can do this, how do you balance that advantage? Should we allow all the other mains to heal, so we have a balance there? No because that's what creates the individuality between the classes.
THERE ISN'T SUPPOSE TO BE A BALANCE BETWEEN THEM.

Azure Fang is the only class that has the potential to crowd control an entire line up, how do you balance that? Should every class have the potential to crowd control an entire line up somehow? Do you see the pattern here? They're not suppose to be replicas of each other, that would be pointless of 4 DIFFERENT classes.
She has her glaring strengths and she has glaring weaknesses, like any other class does- the only argument I'd place in favour of water mine is that she has a very small pool of line ups that she can really shine in, but those line ups are incredibly strong line ups but that's what also makes each main strong & weak, it's not the talents they hold but the line ups you create around them, if you don't have anything that your Main c*e very effectively then, yes, that main can look incredibly weaker than other mains you fight because you can't utilize that mains strengths, that's the reason we're able to switch between mains and are not locked to a specific one.

Out of every class, I'd pick Earth Main as being the weakest he has straight up insane ability to buff, generate chakra & shield the crap out of his team- but he is incapable of utilizing any ninja that clears buffs- 5 Kage Madara/Han will never be used by him & is a ninja that completely negates everything an Earth Main can do in just one Ninja, think about that.
Although he is used heavily in CN & at later powers, because people have noticed that his shields scale so hard that they basically become 2nd life pools- but he still has a such a harsh counter- just like any of the other 4 classes, this fixation on you wanting to play Azure Fang & that you need it to do everything is counter productive & wont get you anywhere.

Pick something you can utilize, enjoy & play it, don't fixate on what something else can do & why your main should do it because that's what you want to play, if you think Mirror Vision is better, use it, if you think shields are better, then Earth Main it but don't come into the forums like you have the solution to the balance & buffing Azure Fang is the core solution when things don't work out for you.

Play longer, learn more about the game- It's a rock, paper, scissor experience & that's the way the balance should remain, this isn't world of warcraft where everything should do everything..

Also I glimpsed through your "desired buffs" & your neurotoxin improvements clearly confirm to me that you have very limited knowledge about how to play the game & most likely haven't even played for very long, I'd recommend you play through it for a few more months & work on some Ninja like 5 Kage Madara that go very well with Azure Fang just to see how *ly broken Azure fang can actually be.

A lot of what you suggest would put Azure Fang miles a head of every other class, it actually made me chuckle at some of the things you came up with- you literally want to rain dominant on Azure Fang, bro, branch out a little.