I don't know the TESTED answer, you can easily test... Start out with a dragon at 120 wrestle (trained), let it die a few times til it's at 119. Re test dmg/to hit chances. Let it die some more til it's at 118, retest. etc.
It would make more sense to me that instead of large chunk steps it'd be a formula and every point of wrestle has some small influence... but I'm just pulling that out of my butt.
Regardless, you are gonna want a dragon with 120+ effective wrestle after training anyway. And high magery would be a nice bonus too.
Go tame yourself a half decent one and then keep upgrading as you find them and hand your old dragons down to newbie tamers in your guild. Or let them loose in newbie areas and watch the chaos ensue. >
