Disclaimer: I am a completely mediocre 400-hour scrub at best.
I don't "feel" like there's as much reward for conventional rushdown tactics in Skullgirls because the foundation of prophylaxis for that sort of stuff is generally:
frame advantage > difficult 50/50.
Not enough players (myself included) really know the frame data for this game well enough to be afraid at key points in pressure strings to sit still long enough for the mixup.
Also, Pushblock is really good when used intelligently, Absolute Guard is really accessible for negating some of the better high-low 50/50s, invulnerable startups are really good, hit-stop supers can buy your way out of a mixup, and the strength of disjointed hitboxes or armor on some moves are all working against it. All of that plus the relatively unused alpha counters and PBGCs that we'll likely see more of in the future as the general community gets better and starts catching up to the higher level guys.
As a defender, there's too many reasons to be impatient in this game so rushdown always feels like failed pressure dragging on as filler rather than "he's scared to push buttons because i'm at advantage and he'll get bopped, now I can present the mixup" like it would be in other games.
At this point, I believe the best options for maintaining pressure rely on assists to close gaps created by pushblocks rather than cancelling stances/flight etc. on the point character. I would strongly recommend practicing/understanding the extension of pressure with assists as a priority over practicing/understanding flight cancel extensions.
For Painwheel, Negus Eyoel is probably the best example of taking the space from a pushblock for your point's safety and then sending an assist in to present point pressure again, or using the assist close to the end of a string to extend pressure if they don't pushblock. I've studied just about everything I could find of his.
For Peacock, I have no idea why you want to rushdown tbh.
For Squiggly, watch Yaya. He doesn't really rushdown so much as just do his best to make sure the first initial aggression is the mixup presented directly (i.e., with no pressure strings blocked). If there's pressure after that, it's generally another mixup that was enabled by an assist. In my opinion, FuzzySnugs is also really good to watch as well. He is extremely direct about low/throw and high/low mixups.