When discussing names like Gretzky, Lemieux and Ovechkin--I think it's safe to say that all three of these men are all-time greats and would have succeeded in any era. Selling any of them short is disrespecting their talent.
In the 90's, Ovechkin would have been a combo of Pavel Bure and Keith Tkachuk--both were high-end goal scorers of their era--and he would have been better than either of them individually. I fully believe that.
However, I also agree with
@Sentinel in the fact that Ovechkin would have paid a heavier, physical price to score his goals back then. Due to his style of play, Ovie would likely have been in the middle of feuds the same way players like Lindros and Neely were. Yes, Ovechkin is a machine. But also yes--he does NOT need to engage in hand-to-hand combat on the ice today with madmen like Scott Stevens, Ken Daneyko, Bryan Marchment, Ulf Samuelsson, Derian Hatcher and Darius Kasparaitis. Those guys were featured on MOST WANTED posters but there were also less-popular assassins-for-hire that would have had no problem targeting Ovie's knees back then--guys like Michel Petit, Rich Pilon and Igor Ulanov.
Case in point--last week they asked Chris Pronger--
"what would have happened if William Nylander scored a goal between his legs in the crease while you were on the ice?" He said, without holding back, that he would have slashed him between the glove and elbow pad--getting all bone and meat to take him out. If he tried it a second time, he said that he would have been on the IR. This was the mentality back then.
One thing is 1,000% indisputable--scoring goals in today's NHL is far less physically taxing on the human body than it was in the 80s and 90s. How would that have affected Ovechkin, per se? We'll never know for sure. Logic says he would "likely" have missed more time. That said, he would still have been an elite goal scorer when healthy--nothing can disprove that IMO.
I also agree with
@Sentinel that Wayne and Mario would put today's NHL through a shredder. Mario literally had to score goals while fighting through defenseman hanging on his back. What do you think he would do in an era where there is no red line and you can't even put a hollow stick on a guy? Does anyone truly think the Fredrik Andersen's of the world are going to shut down a prime Mario Lemieux?? Lol. Mario--even more than Gretzky IMO--would toy with the league today. Look at what a big-bodied Leon Draisaitl is doing to the league right now--and this guy couldn't touch Mario on his best day. Prime Lemieux would put up 145-160 today. Mario in 3-on-3 OT? Jesus.
All of that said, what Ovechkin has done--and continues to do--is insane. I have my money on him breaking 894, which would officially make him an NHL demigod.