The uncharged doesn't allow for insane sdi like a charged one, but it provides time for follow ups since grounded ending lag is shorter than the hitstun. They don't airdodge the bat, because I first tried it out on CPU's before anything else since they like to airdodge the minute they get out of hitstun in the air. Because I end the jab lock at around 60%, it's enough to get them off the ground, but not too much to put them out of your bat range. I believe the reason they can't airdodge is because they're too close to the ground. And yes, I know a shield comes out in like, 2 frames, and a spot dodge is like 3-6, but again, the hitstun wouldn't allow it, because on top of that you've got the other character's landing lag animation as an extra (although small) frame wall between you and their defense. There may be a way out with marth (Haven't tested the dolphin slash, does it come out faster than the shield?), but I know it works with snake, due to his height AND weight.
The best way to get results is to try it out and see. I'd say spacies, but fox is too short, and I don't know if their fast falling is a factor. I don't want to rule out all heavies, but neither dk, ike, bowser, or rob should have a move that comes out fast enough, but I'll go over the frames and stuff today and get back to you.
But really,
Any character tall enough to get ness of the ground in a grab can be hit with the uncharged flash on the ground, and when timed correctly, anyone caught in an uncharged flash should be prone to a follow up without opposition.
Edit: Last tournament I was in a crew battle where Ifull flashed fox's phantasm, so for predictable recoveries, I'd say it's worth the lulz so long as you're at a safe distance. It can usually force a ledge recovery, leaving you protected from most character if you spaced yourself from the ledge correctly should you not hit them.
Snake's recovery
firefox/firebird
pkt2 (both chars)
rob's recovery
Dk's recovery
Diddy
etc. The list goes on. if you can get it in front of a horizontal recovery, or above a vertical one, it'll s*** on them or force a ledge grab.