i just spiked the CPU today with sonics d-tilt while they hang off the ledge. its very rare anyone hags on the ledge after invincibility frames so no wonder people havent seen it before
are you sure it wasn't a stage spike?
cause then we'd have to add spring spiking to the list lul. I'll go check that right now.
Sonic's F-air sometimes launches at a semi-spike angle, but I haven't been able to pinpoint the exact situation for it - height, direction of movement, placement in Sonic (guessing sweet spot is the best, but it could be around the hands for the semi-spike), grounded opponent vs midair... etc
His f-tilt sometimes gives a spike effect, but I think that could just be on grounded opponents. I have done some semispikes with it (first hit only) but I'm not sure of the exact conditions for that either, other than Sonic between low aerial opponent and ledge.
U-tilt has a downward motion for comboing people before the last hit. It's possible to 'tip' it so that only the first hit (sends downward) works, but it's definitely meant to combo into the last hit, so it's probably too weak for practical spike usage.
I'll post it here when I can get them to work somewhat consistently.