Strong Points:
-Wide variety of tools at his disposal
-Fastest walk speed in game
-Great tag synergy with his heavy shoryuken since it launches high
-Good zoning and control tools
-Fast start up on a bunch of his normals
-Good wakeup game (him standing up from ground)
-Great oki game (him standing over opponent)
-Great jab pressure
-Good at building meter, doesnt really need to use it for much other than raging demon setups/punishes (having 2 bars of meter will make your opponent respect the shit out of you after the first few raging demons he eats, which can lead to really ambiguous setups)
-Raging demon is the best punish move in the game
Weak Points:
-850 Health (this is what hurts most, though it can be offset by gems)
-Demon flip is pretty bad in this game (unfortunately)
-Somewhat mediocre damage outside the corner (your average punish will be doing around 220-300 damage)
-Can’t combo reliably from his overhead (its a 1 frame link when it hits on crouchers I think)
Partners:
Anyone is good who has good damage from a post tag combo with a jump in, he really doesnt have any outstanding weaknesses except for his weak health and average damage so there really isnt any character who he cant handle. Hes a jack of all trades.
Combos/setups
Just a link or 2 you need to know really, most important one is far st.hk to close st.hp. Most non-corner combo damage will come from hits on standing opponents, either in footsies (hit with a far hk, link to close hp which is special cancellable) or by annoying them enough with overhead hits to make them stop downbacking while you are pressuring them. Special will be LK tatsu, which you can follow up with a shoryuken (mp for solo damage, hp for reliable tag cancels) You can also throw in a normal of choice after the LK tatsu and before the shoryu, a close standing mp is pretty easy to put between them. IMO the absolute best way to use meter is by keeping it and making the opponent respect your pressure by making them eat a few raging demon setups first. After that, they will more often than not be scared of said setups when they see you have 2 bars of meter, and you can then force them into making mistakes by ‘faking’ said setups, and push them into heavy damaging combos either with or without meter (depends if it would kill or not is what i say, if by tag cancelling that shoryu at the end of the combo you can finish the deal then do it, otherwise keep the meter to keep this ‘respect’ game going)
Some stuff you can do in the corner can be insane damage wise compared to the rest of his mid screen combos, especially if you throw some EX moves in there (EX tatsu, EX red fireball) A good setup for example is making them not downback with some overheads, then do cr.MK xx EX tatsu, far st.HK, close st.HP, red fireball, st.mp xx hp shoryuken, its easy to pull off, and it deals some decent damage. (some characters can get better midscreen meterless, so its not all THAT good, but take what you can get)
On getup, his fast walk speed will allow you to get a throw in on anyone who decides to roll pretty much on reaction which is a great asset to him, especially when you pair that up with his great sweep. This will usually mean they will stay in place, which can set you up for ambiguous cross ups or demon flip stuff (like faking a charged demon flip, wait for them to roll, and then CADC to walk throw them, or flipping on them for a throw/kick)
Honestly the sweep/throw mindgames work well enough here too, or the cr.mk/throw mindgames rather, since you can get more damage out of that, but it works somewhat better for ryu because he has his derp cancellable sweep and an awesome chargable fireball which you can CADC to a throw or an overhead or whatever you feel like, but akumas mindgames work reasonably well too, and they are closer to the classic shoto mindgames (empty crouches/crouch jabs with fireballs, bait AAs, etc.) If you have 2 bars and you feel like messing someone up on getup, you can set em up for a raging demon too if you see they arent rolling. You can also use his zanku (jump) hadoken to set stuff up on getup, either a roll or a block from your opponent.
His best raging demon setups as far as ive seen (been practicing him for 2 days… already kicking ass with him though lol) are the ones where you are jab pressuring into a far st.hk which you cancel into a raging demon as early as possible (before first hit) OR after the first hit with a slight delay, just make sure you avoid the time period when they are in blockstun, or another one is when you throw a zanku hadoken on getup (or in general) and see them not roll but try to block it.
Overall I would say he is a somewhat undervalued and underused character in this game simply because he isnt as good as he was in SSF4AE, but he is definitely still a force to be reckoned with, with a great toolset which can stand up to one way or another to pretty much any character to a certain extent at least. Do note that this is coming from a 3rd day akuma in practice, so I may overvalue him at the moment, or miss a few points, as in, not see his faults clearly, but Id say my summary is pretty accurate.