Sonson has a Sentinel infinite. Not huge news (GameFAQs was the original source, though I’ve not seen video or confirmation, and several people have laughed it off). It’s very simple, a jumping-forward infinite. It is:
The initial LP has to be done on almost the first frame of the jump, and hits Sentinel in the knee. The following LK, MK must be done almost as fast as possible, so that the MK will hit Sentinel in the head right before the apex of the jump. Too long, and it goes over his head. Follow it with the HP - maybe incorporating a very slight, 2-3 frame delay, then after the third hit, execute the HK so that Sonson kicks Sentinel in the shin.
The trickiest part is getting the HK low enough, and following the jump with the immediate LP. The nice thing is that if you screw up it still combos, and you can follow that with just about any standing combo you want. Lather, rinse, repeat a few times, then either combo into DHC with the Staff super, or use an assist to attempt to reset the combo or end with another super.
I talk like I’m an expert, which I’m not. I’ve only just managed this, but I got 3 reps at my best, which means it works. It also seems to work both in corner and along the way there. I’ll try to get a vid made as soon as possible, but I think it’s worth documenting for the people here.