Take this with a grain of salt; I'm still pretty new.
Against Parasouls, I generally focus on slowly advancing and pushblocking her bit by bit into the corner. The only way she can really get into you is either dashing in, dashing behind an assist, jumping in honest, or jumping in with a j.LK/j.MK crossup. The first three can be turned into a bad spacing play for her with judicious pushblocking (i.e., slowly walk her into the corner) and the last one is pretty uncommon/hail-mary if they don't set it up well.
Parasoul's j.LP, j.MP string is usually enough to discourage air-to-air play for painwheel, but if you're really confident they'll do it, tiger-knee a LK buer (2367+lk or 2369+LK depending on her angle/approach) and you'll catch them. For whatever reason, air buers seem to work better in priority fights than standing HK-Buer. Just don't be wrong or do too many, as it's a quick way to get airthrown.
Corner Bella is corner Bella; I think you really need to know her and how to defend against her more than trying to create an opening with aggression or counters/reversals that Painwheel really doesn't have. The reward for reading a throw should at best be a j.MK/j.HK into combo, or at worst a jump/fly into crossup guess attempt. The reward for reading an AAthrow is pretty much anything; anti-air throw whiff lasts forever.
I think most Painwheel players (and really, most Skullgirls players) tend to be overly focused on aggression and forcing their game on to all characters they fight. In our case, fly cancel rushdown is probably the single worst possible idea against a character with an invincible AA/Reversal and high-priority air to air conversions. Similarly, it's a pretty bad idea against a good Bella player that can see the flight approaches well enough to either judiciously AA-throw or reversal Dynamo when we're overextending pressure.
That said, in both of these matchups, we can fly circles around both characters and get a lot of rewards for pushblocking/reading, which is fine by me. Painwheel does a lot of damage and is really mobile, but not all of her damage has to start by exploiting her mobility. If it's shut down, look to make reads and punish.