Ugh. What's the matchup of Valentine vs Parasoul?
It's pretty even as far as I can tell. I find it difficult to contest her in the air as even though j. HP is fairly strong for Parasoul, Valentine seems to have higher priority on her air attacks not to even mention her superior air mobility. It mostly comes down to your fundamentals and push-blocking so she never gets free offense on you.
She has to be pretty close to do damage and has to take risks getting to you since I find her ground game to be somewhat weak due to the fact that she needs to be pretty close to be able to get her launcher in which sets up most of her combos. Her throw is also very strong, but again, close range.
Because of that, I mostly try to play a safer, neutral game. Napalm Shots help a lot, especially MP because she likes to approach from the air. Learning to cancel jump attacks into air Napalm Tosses can also help as it will make her offense more risky if they go off and can open up combo opportunities there. Neutral j. HP is fairly strong as well because even though her air attacks might have higher priority you put yourself at little risk since you're less likely to directly move into the range of her attacks.
Valentine has the scarier mixup game once she's up close, but on the other hand Parasoul has the tools to make her mixup game hard to start. It's an even matchup as far as I can tell.