I recorded Ken's Jump in Hard Punch too see which Normals could stop it.
Ken's jumping Hard Punch has an extremely large vertical hitbox... I'm willing to bet it is the absolute best Air To Ground attack in the Game.
This is good because if you Stand Up he can hit you right after the Apex of his Jump. Which means you need to DP it like this (
) ... other wise you'l stand up and get pounded on by that Gigantic Fist if his.
1) I tested a bunch of Normals that would stop it and Cammy's Back Medium Punch seemed to have to highest success rate... not because of its Priority (which it does have in spades)... but because of its Speed... its a 4-Frame Medium Normal... Cammy's also pretty short... causing the first active frame of some attacks to whiff (Moonsault) meaning one extra frame to Anti-Air. Stopping Ken's Jump ins was a Breeze with her. There is one catch however, its Hitbox is abit narrow so it will only stop opponents who are directly above her head.
2) In 2nd place I say Zangief's Standing Lightpunch is absurdly good...which is weird because the April Balance Update was suppose to eradicate Anti-Lights... and maybe it did because No matter how hard I tried I could never get Standing light punch to properly beat Ken's Jump in Attack while it was active... I either get hit or the Light punch always interrupts the attack (which isn't true Anti-Airing)... but who cares... it works and the Quick recovery is great for Zangief because he's a grappler...
3) and in 3rd place I would place Ryu's crouching Hard Punch as an okay anti-air... which is weird because his fist doesn't actually go above his head so I don't know why this works... its still trades like crazy against jump in attacks but doesn't straight up lose as often as other normal anti-airs do.... its the best one could hope for.
4) R. Mika's Crouching Medium Punch is rubbish... you have to whip it out damn early to beat Ken's fist and even then it always Counter Hits... in addition to its weird priority its got a tiny hitbox and inches Mika forward causing both Attacks to whiff.... so why mention her at all ?
Well it turns out trying to sneak away is better than trying to anti-air with her.... crouching Hard Punch allows her to go underneath semi late jump ins. Crouching Hard Kick lowers her hurtbox and if done late enough can even anti-air jump ins the were mean't to beat crouching medium punch.... if you must do it early then do it very early because it doesn't have crouching hard punch's Recovery.