I've noticed a bit of a trend. It seems like all the grapple/hold based characters (i.e Bass, Tina and Bayman) have been noticeably buffed. Bass and Tina seem really good now especially with most people's counterholds being nerfed now. From what I've seen of Helena, even with her nerfs, she still seems very effective.
On a different note, is it me or can Rig be a bit of a cheapass? His strategy always seems to be to just mash out random kicks as much as possible.
Based on what I've played with Rig, I find that he has very short critical hits/stuns to the point that getting a red stun is actually pretty tricky. He seems like his entire strategy is similar to Ayane in making characters try to attack him only to whiff or eat fast kicks. Rig gets a little trickier because of his mid kicks (of which he has fewer than most characters) require a different hold than typical holds. Rig, as far as I can tell, only has one natural launcher (33K) and the altitude is so low you can barely make use of it.
Basically, Rig's strategy is to get you to come at him and then tear you apart. And if you think that just blocking his kicks is going give you an advantage... well he's got tools for that too.
He has a really good whiff punisher (6H+K). His P6P and 4PP are really great. His P+KK is really strong, but his Bend Knee (BK) P is really slow and has terrible recovery. It puts the opponent in a sit-down stun, but I can't find anything to follow up with. His 2H+K has a better sit-down stun on counter hit.
Kokoro is a lot differently in terms of what you can do with her. her stuns are different and her launchers are slightly different in their properties. that 2H+P,P or even that PP2KP is much harder to land as a combo finisher now. it takes some getting used to her 6P+K that used to just be 66K (i think). her 66P+K is much different and is a much more useful tool do to her stance follow ups and even just the threat of it. on a side note i believe Kokoro's Critical Burst move is one of the best in the game mainly because it's one of the fastest. the only thing about it is that it is a beginning of a combo so if you accidentally press 6P after a Critical Burst then you just lost a lot of free damage.
Her 7P critical burst is 12 frames. For some perspective, the fastest move in the game is Eliot's 7P at 9 frames. All PPP... combos generally start at 10 frames. Basic 'punisher' zero-directional input throws are 5 frames.
After looking through some of the Kokoro videos I posted I noticed that players were using her 3K and 3K2P and PK2P moves. Back in DoA4 and even DoAD these moves were pretty cruddy. So I check them in training mode and... they're still pretty cruddy, but not that bad. 3K is still -3 on hit which makes it safe at a distance (its also her best reaching move). Her 2H+KK is +0 on hit, but lots of frame adv on counter/critical hit with the forced sit-down stun.
Kokoro's 7P also has an unlisted (she has a lot of unlisted moves, by the way, everyone does but Kokoro has the most), follow-up. The command is 7PKP, you can delay the P forever. But the entire string is mid-low-mid, so be careful.
6P on hit is -11 and 6PP is +4 on hit, but doesn't combo naturally. As far as I can tell, no one is able to counter 6PPP if it hits on counter, and it puts the opponent in red critical, allowing for an easy critical burst. Provided that then can't slow escape or hold out of it (I don't think they can).
Other unlisted moves include Kokoro's Sidestep P and 33P being the same exact move and they both have the same follow-ups. 4PK*T, 3P*T, PP*T, 2K*T, P2K*T, 9PP*T, among others.