cl. A can be canceled into his f+A, A command move, and chained into his cl.B
cl. B is a low attack which has a close activation range.
cl. C is one of the fastest close normals with a start-up around 2 frames. It's good for a quick close punish, and for stopping opponents jumping above your head.
cl. D doesn't cancel into anything but it's good for a quick anti-air to stop opponents from jumping out of the corner.
Standing
Stand A/B/D are not cancel-able at all.
Stand A is 4 frames on block which is a good for poking at a close range to bait and block Guard Cancel Attacks. The distance on the stand A is rather short, though.
Stand B is a good close range poke that is aimed at the opponents lower midsection. It is fast, had great recovery, and can be used to frame trap opponents with his qcb+A rekka.
Stand C has a good attacking distance but poor recovery. It's good for moderately far punishes in close range. Be sure not to freely throw this out on whiff because its recovery is poor.
Stand D is good for preemptively stopping hop attacks but it's whiff recovery is bad.
Crouching
cr. A/B/C are cancel-able on block and on hit.
cr. A is chain-able into cl.B and cr.B. It has good range and is also neutral on block.
cr. B will be used a lot for his high low/pressure, rush down and for starting combos. When running at your opponent, use this to stop your dash and to throw out a quick low attack, next to hyper hopping j.C.
cr. C can be used to anti-air opponents but it might trade sometimes if timed incorrectly.
cr. D isn't cancel-able on hit or on block, so whiffing it or having it blocked can leave you wide open. Use with caution.
Jumping
j. A has a rather sharp downward angle which can be good to use next to his j.C because it start quicker.
j. B is had a very good horizontal range which is good for air-to-air attacks, and stopping incoming hop pressure if used jumping neutral, or jumping away. Be careful because it whiffs on crouching opponents.
j. C is a very deep jump-in which will always hit crouching opponents, no matter if they are using a normal attack that can be used as anti-air against certain jumping attacks. It is also fairly hard to anti-air against as well on wake up. Use it to fully utilize his annoying high/low mixup game on a fallen opponent, or to pressure at close range next to his cr.B. It's a little weak as an air-to-air normal, so use j.B for that purpose.
j. D can be used as an air-to-air attack during certain ranges, and as a good jump-in, but it may miss on crouching opponents if performed too early.
Blowback Attack
Iori's shoulder thrust is cancel-able on block and hit, which has a fair good activation range. You can try to use it as a preemptive anti-hop attack, but it isn't guaranteed.
j.CD comes out rather quick, and has a good downward angle which is good for jump-in and hyper hops. It whiffs on crouching opponents though.
