I'm not saying I'm an expert by any means, but I have a few combos I'd like to talk about. I've no idea if they're changed in AU though.

[hider=SNIPING SNIPING SNIPING SNIPING HAMAON]Yosuke's 2C -> 236B -> m-a236A x3 -> Garudyne(?)
I personally like this combo since it (last time I checked) does around 3/3.5k damage, but the issue is that 2C has nasty start-up and it's only really viable if Yosuke has a strong advantage going. You obviously could start it off with something faster, like his 5A or 5C but then you for some reason kill a significant amount of damage from the combo IIRC.

Yosuke's 236B -> 236A (hit near the ground) -> m-a2C
I haven't played Yosuke recently, so I can't remember if that's how it starts or ends, but I remember liking this, and I believe it's one of his challenges anyway.

Naoto's 5A -> 5B -> 5C -> 2C -> 236236B
One of my favorites. I mainly use it to reduce the enemy's fate counters, since every time that super hits it's a solid 6 counters gotten rid of. Two of 'em and Snipe or something and you're set for a Mudoon combo.

Naoto's 5AAA -> Mudoon
A very simple way to get that Mudoon off. Getting a Mudoon/Hamaon off a trap might be better than trying to go for the 5A considering Naoto, but I dunno.

Naoto's SMP Combo: m-a5C -> 5B -> 2AB -> 236AB -> Mudoon -> 214D -> 2A -> 2B -> 236A -> 5C -> 236B infinite
(Personally, I prefer omitting the 2A and m-a5C and replacing them with a 5AA at the start instead)
Naoto's SMP Combo is a pretty significant thing IMO. While I've never managed to pull the whole thing off in an actual fight, I can do it pretty reliably in practice. There's probably tonnes of ways to do the whole combo, but this one seems to be the easiest/simplest way. I feel like the m-a5C is important for something but I don't really know? The 236B's are easier to do when you get a fatal counter on the combo, but it's still pretty simple to do if you can do a whole whack of quartercircles in a row without slipping up.[/hider]

Also Naoto got an ammo gauge in AU? Guess I can't cheese the AI with Snipe anymore.