Between 147 - 154 maybe Cuevas & Trinidad if they landed flush. Although if Hearns couldn't K.O Leonard at 147 I don't see anybody else outside of SRR doing it. At 160 however, I wouldn't be surprised to see Hagler stop him in a 15 rounder back in '84.
Don't like Leonard, always found his personality completely contrived, but there isn't anybody in the history of the sport below 160 pounds who'd have had a real shot at stopping the guy. He was an incredibly hard man. If Hearns' flush right hands didn't take him out, nobody else from 154 down could have turned the trick.
I do not favor anyone to KO Leonard at 147. A few can beat him, Some can knock him out... But that would be a surprise not an expectation.
But did Hearns land flush? I seem to recall that SRL turned his head at the last second, slightly reducing the impact. I haven't seen the fight for a while but I don't think Tommy used the left hook much. Really, Tommy's left hook was seriously underrated. Virgil Hill reckoned Tommy hit him harder with the left hook than the right hand when they fought at LHW and he killed guys to the body with it. Anyway, that's why SRL was very resilant, he had the chin and the defensive smarts to negate some of the power coming his way. I can only see SRR, other than Hearns, having a realistic chance, although if SRL gets careless there's a few other guys in with a shot. Although I didn't like a lot of his politics in picking opponents, SRL was a helluva fighter.
The even more egomaniacal stone killer Robinson would become enraged at Ray trying to usurp him, resulting in a horrific early beatdown. Hopefully.
People make me chuckle when they make out as though Robinson would destroy Leonard with ease, not a cat in hells chance. The fight would be dynamite that's for sure.
prime anyone would be hard to stop including Norris. it takes a one punch artist like Jackson. otherwise it takes an accumulation. Leonard wouldnt get close enough often enough and since Terry is quicker on the draw, he would win on points only 3 people I've seen who can stop Ray at 154 - Hearns, & Jackson, possibly McCallum @ 160, the list improves considerably which is probably why he didnt accept any defenses of his title
yeh i purposely left 160 out because i think the list would be alot longer. and it wouldnt be challenge.