Nash would win.
"Going back to tough guys, one of the last tough guys in the business that I can think of is Kevin Nash. You never saw anybody pick on Kevin Nash. The Steiners didn't do anything to him. Nobody did. Kevin Nash is a tough kid too." - Ric Flair
https://youtu.be/5ZAjlSv8Wes?t=853"Tough guys of that era? I'd say the two toughest are Kevin Nash and Ron Simmons. Kevin just plain tough. Never took shit from anyone. Nobody fucked with Kevin Nash." - Ric Flair
https://youtu.be/eodsZ3AX5VQ?t=301On the three toughest guys in WCW: “I know Scott Steiner is tough. Everybody knows that. Bill (Goldberg) is tough. (Kevin) Nash is tough.” - Tank Abbott [Alex Marvez interview on
WrestlingObserver.com - 6th September 2000]
Things We Learned From Scott Steiner: Live & Uncensored tour at The Garage in Islington, London. Asked whether there was someone who he would think twice about before meeting in the parking lot for a brawl, Steiner said there wasn't one. Sure, there were tough guys in every locker room he was ever in, but nobody he would be scared to fight. The Big Bad Booty Daddy did name-drop Haku/Meng as someone who was known for his toughness & also said that Kevin Nash would be a tough fight, given his size & experience as a bouncer, but Steiner didn't say whether they'd be able to take him or not. [WhatCulture - 22nd March 2016]
“Back in the day we had some tough son of a guns in our business; Muraco, Tonga, Neidhart... Even Kevin Nash bailed me out of a couple. I was up in bar in Edmonton, Alberta, Canada. This girl met me there. Turned out this girls boyfriend was in there, & we got into a skirmish. So the best I could do was just hold onto the guy up against the wall, & I nodded over to the boys and Kevin got it real quick. Kevin came up and busted it up. My wife is in the kitchen so I don't want to get to graphic. Kevin came to save me. I mean we were a brotherhood. - Jim Powers [PWInsider Elite - 22nd September 2010]