wombat: the recovery on a whiffed PO 8B+G is massive.
an analysis of 66B on block:
- going into PO makes taki do a huge backstep, far enough to make counterattacks like AA, BB, 2A, etc whiff. pyrrha's 236B will whiff most of the time, but i've had it hit once or twice (iffy hitbox?). PO K serves to move natsu backwards slightly more, and to take her out of PO.
- hover/fake hover keep natsu in place after her humongous PO backstep, which means that the aforementioned counterattacks still whiff. HOWEVER, the opponent typically is able to guard in time before hover B hits. unfortunately hover A whiffs too much (the backstep is too huge) for there to be an actual mixups. i will say, though, that pyrrha's 236B moves forward enough to make the mixup valid.
what you really want to do is fake hover PO B, which will definitely hit on block and give you +9 into whatever. don't try to do fake hover PO B+K as a mixup; natsu has an enlarged hurtbox during the move that allows moves like pyrrha's BB that would normally whiff to hit her instead. also PO B+K tends to whiff (HUGE backstep).
- moves with good range like pyrrha's 3A or a delayed 66B, will hit natsu out of hover/fake hover and PO K. but please keep in mind that you can block them if you simply don't go into PO.
- there is only ONE move i know of that beat all these options: natsu's 6A+B. the i16 speed, combined with the double hit, mean that natsu gets hit out of everything in PO, and gets punished as well (66B is -16). please let me know if you find other such moves.
but even then, 6A+B can be evaded by PO 8B+G if you really want to. i would hesitate on using it as a primary evasion tool though, because while it actually evades counterattacks like AA and BB pretty well, it leaves natsu directly behind the opponent with a massive recovery from the whiffed stalker throw... essentially guaranteeing a back throw for the opponent.
that's a rough idea of how PO works with 66B. i'll leave 6A+B PO to someone else instead, or i'll do it over the weekend.