For Helena and below, I haven't fully tested this, but 6PP6K PPK 2T is the best option. PPK in open space works great off a HC 9K it does 98 dmg while ending with GS does 108 and 4T does 100. So PPK is a nice option. Especially when it can possibly go up to 118 if the opponent doesn't tech. I at first disliked Tinas blowback which she severely lacks. This is a good thing cause now she got a vortex. In open space and closed space against majority of the cast. I was doing 9PPP for higher launches. I can't believe it took me this long. To realize in open space PPK is good. Now I hardly ever use 9PPP.
I'll mess around with it and see what I get. I haven't been on DOA much since DBZ Xenoverse came out XP.
The 9PPP combo reminded me of a PL combo I'd mess with in training. If I remember correctly, this would essentially be her most damaging PL combo as long as they don't tech:
PL>9K>9K>6PPP>GT
It's basically her little whiff throw vortex in PL form. If they tech, GT will whiff, but you'll be at a slight advantage (I wanna say neutral but not sure). If they stay down, then you get a lot of damage (127dmg on CH compared to her PL>9K>9PK>GS which does 122)
Also, if you want to use the 3P variation of the vortex Rubin mentioned on higher launches, delay the 3P so that you hit the opponent when they're a little lower to the ground. This will help avoid giving you the whiffed GT animation, which would put you at a disadvantage.