I think that the FFC is invincible while Frank is jumping up only (Zansam has the exact data). As for the assist, we used the ground bounce because its simpler to setup that way and Zansam and I both use teams that have a ground bounce in it. Its mostly a proof of concept, but I am sure properly timed Doom missiles can pick them up off the ground. Possibly something like a launch, H Tools into relaunch, land into missiles and then get a wall bounce off the missiles into a second wall bounce? I would have to play with it, and next time I sit down at my console I’ll try to find something and possibly make a quick fun video on that.
For the dash outs, check the escape list in Zansam’s post :-p
The assist doesn’t need to have groundbounce. Nova’s works so well because it -always- ground bounces, so it allows Frank to use his and then Nova can still prop them up later. Other ground bounce assists don’t offer the same potential For basic setups you need an assist that can let you combo extend while you OTG with snapshot/roundhouse (Dormammu black hole is a good example) then you can let frank groundbounce OTG to setup Tools M himself. Doom rocks would probably work better as a mid-combo extender to preserve groundbounce, though you might be able to do Roundhouse + rocks into tools M at the end, not sure.
The practical consideration regarding air dash is really whether or not it has startup. Nova/Spider-Man/Zero/Ammy etc all have startup, so that’s what stops them from getting out. Those with the 8 ways 0 startups can always get out, and even the two ways as long as they forward tech + dash forward. Iron man’s an odd case in that his only 0 startup airdash is straight up; anything else he gets reset.
FFC is invincible during its startup (which is I want to say 10 frames, that I’m not 100% positive on offhand). It has 5 active frames, the first two of which are invincible. So it can be stuffed, but not at the beginning. Since the hitbox isn’t known (not even the Vita version shows throwboxes -_-) it’s hard to establish if a move could have a hurtbox to stuff him during the reset. It’s pretty unlikely though.
I don’t know if this is helpful or not, but I had seen this chart in another thread; it shows data on assists and HSD immunity. Since you guys are mentioning assists that break the ground bounce rule, this list actually shows which assists do that, as well as any other special properties for all assists. Hope this helps!