Against Iggy
You are going to be relying on your whiffpunishing and neutral game in Stand OFF a lot instead of mindlessly rushing in, trying to counter Iggy's approach with buttons like 6B, 2C, S.2A and S.5B, with occasional cancels into 236S if you are Stand OFF, they will be very reliable in this matchup for counterpoking and hit confirming. You will usually use your Stand ON normals for anti airing. For approaching use normals like d.5A, S.d5B J.C, as they lead to full combos on hit and hit Iggy when he switches back to Stand OFF, try to avoid using your Stand ON air normals against grounded Iggy, as he can react to it position himself in S.OFF below you and grab you. Generally avoid abusing normals that whiff on Stand OFF Iggy while he's Stand ON, he can quickly switch it off and then go for a punish, these normals include 66C, 5B, 5C, 3C, S.5A, S.5C.
When Iggy starts stalling the neutral with his sandballs your best bet to stop it is to either approach him really slowly and looking to hit him out of the air with S.5A or try and time your 66C so that it hits him in the air, this however will most likely cause a trade but it will be in your favor, obviously avoid doing that if you're at a magic pixel. Iggy's s.[4]6A is actually punishable on both hit and block, you can punish it with either S.d5A, 66C or 6B, his s.[2]8A doesn't really have much recovery on its landing so you will have to properly time your punish. His 643214C as okizeme is unblockable but it's still escapable, you will have to take a hit and hold jump after getting hit by his J.C or a ground normal, doing this lets you save more health than you would've lost trying to block it.
By far the biggest problem in this matchup is your oki, because of Iggy's hurtbox it's practically impossible to make him guess on his wakeup, however, you can use a knockdown in a Tandem to cause an unblockable reset, as shown there - (https://twitter.com/swagskheletor/status/1122093420669997056?s=09), outside of that the best you can do on his wakeup is to just meaty him with 236A or go for a grab.
Iggy's weird Stand OFF hurtbox also means you will have to alter your combos:
In s.d5A s.5A s.5A s.5B xx s.236C (2 hits) -> s.214a !SC instead of going for a s.d5C you will have to do 66S 6B then continue the combo. Your hyper hop J.C doesn't work from every range on Iggy, so you will be either going for 66A 5A or just walk up and 5A if you are in the corner, however, there's still a way to land HH J.C by negative edging 6B into 214C instead of using 214B, this however means your stand will have longer recovery so you'd have to make up for it by always hitting 2 A buttons after HH J.C lands so that you can keep comboing properly with 6B xx 214B/C. You can also land HH J.C from 214B if you confirm from 6B from far enough. Below you can find links to combos that work on Iggy.

https://www.youtube.com/watch?v=PORI9K9-w38&t=100s
https://www.youtube.com/watch?v=fDwD10frTcQ
https://www.youtube.com/watch?v=c7w2x2t2buY&index=12&list=PLUqjU6EQxWbIIaK8aJSsFSurB4oQeglKW