Curious which matchups you have him good in? I've seen that clone can give nitara fits, which is nice. Just curious how else he can screw with the higher tiers.
Sure thing, Sub vs Havik is heavily in Sub's favor even though Havik is busted now. It's mainly because Havik players have switched to Motaro instead of Sub kameo so zoning is
much easier. Plus, Havik traditionally relies on his projectiles to get in, but with Janet or Scorpion kameo with Sub, you can full combo punish every projectile for 25-40% damage. Havik also can't Roll to get past your projectiles, either getting hit or freezing for a moment letting you punish. Lastly, even with his new Divekick, Havik has extremely limited aerial movement and so can't get past klone. Oh, and using Scorpion can let you dodge the Tether Snap.
Nitara, like you mention, due to the klone. If she hits you, you explode of course, similar to Havik, but Sub counters Ferra users well since with Janet or Sonya (I suggest Sonya for the extra air control), you can full combo punish all the 50/50s with gaps (not Homelander though, since he's generally not using Ferra that way).
Similar to Nitara, you can blow up Scorpion with Ferra and his B3 50/50s. You can also full combo punish Spear in the neutral which they love to use (I suggest Janet against him for both metered and meterless Slide combos). If Scorpion uses Jax, you can full combo punish most of his strings into Spin + Jax attempts, hitting Jax in the process and stopping the Slam. That all said, I wouldn't say Sub has a winning MU against Scorpion like he does Havik and Nitara, because Scorpion being able to teleport behind your defense is a pain, but more that they both have effective tools against each other, so it's a 5:5.
From the tier below that, Sub has always been good against Reiko if using Scorpion or Janet to full combo punish projectiles, and the same against Cyrax who is trying to Goop you. And once Cyrax is scared of doing that from eating near 40% from a slide, they'll have to rely on their buttons which aren't the best.
Lastly, Kenshi you can out zone / punish his zoning, and worse for him, push him away from Sento using Slide. At that point, he has no wakeup and will generally be shredded by 50/50s from Sonya. Plus, Sonya let's you full combo punish the gaps on his main footsie string and some others.
So, favorably MUs against about half of the 10 and most of the rest are 5:5s. Homelander is obviously busted, and a lot of the top tiers can put you in a blender for sure, but the ones I've listed are generally easier to keep away. And, as I'm sure you can tell, a lot depends on the kameo you play. Hope that helps!
P.S. I'm not sure about the MU against Sektor yet. On the one hand, seems similar to Sindel who can be annoying with her tiger knee projectiles, but on the other, using kameos that lock down the air like Sonya or Scorpion from behind seem effective and/or full comboing her with Slide right before she lands. I will say the fact that Sindel has moved away from Sub kameo to Tremor helps us (as long as you don't get hit, lol), and Sektor doesn't seem to use Sub kameo either, so that's good, too, but I need more matches to see for sure.