WCW's Bash at the Beach '96. Rey Mysterio, Jr. and Psychosis were booked to open up the show. Mysterio and Psychosis had wrestled each other all over Mexico and Japan, and even in ECW, but mainstream American audiences were unfamiliar with them. They proceeded to put on arguably the best match against each other they ever participated in (and according to many, their best match ever), completely won over the initially lukewarm and disinterested fans. The highspot of the night and the finish of the match was Psychosis going for a move called Splash Mountain, a top rope Crucifix Powerbomb, only for Mysterio to deliver a mid-air hurricanrana that brought the fans to their feet. Although high-flying moves have gotten more acrobatic in the days since this match, it's amazing to watch it and see how many modern cruiserweights are following in the footsteps of Mysterio and Psychosis, and it's a Crowning Moment of UnAwesome that Psychosis never became a star like Mysterio did. For the time being, the match can be viewed here.
His match with Eddie Guerrero at WCW's Halloween Havoc 1997 is a classic and arguably put Mysterio on top of the company's Cruiserweight Division for the remainder of WCW's existence. (It also did wonders for improving Eddie's status as an Ensemble Darkhorse until he jumped ship to WWE in 2000.)
Mysterio's match with Chris Jericho at WWE's The Bash 2009 saw him pulling out spots he hadn't done since 2002. WWE itself ranked it the #2 match of the year (behind only Shawn Michaels vs. The Undertaker).
2002 was Rey Mysterio's debut year in the WWE. Let's briefly run down why it was awesome:
He has one of the most memorable debuts by jumping off the top of a steel cage.
Mysterio goes on to No Mercy to have a tag match with partner Edge against reluctant tag team partners Chris Benoit and Kurt Angle for the new SmackDown-only tag team championships, which was an instant classic (and hailed as Match of the Year by many a wrestling critic).
On the next SmackDown, the two teams face off again, this time with a Two-Out-of-Three Falls stipulation; that match was just as good as the No Mercy effort.
Mysterio and Edge defend those titles against Los Guerreros (Eddie and Chavo) and the Angle/Benoit team at Survivor Series. All six of the "SmackDown Six" in the ring together? If that isn't a classic, then what is?
How about his first World Championship win at WrestleMania 22?
In late 2010/early 2011, Mysterio suffered a similar injury as The Undertaker and was told by WWE doctors and trainers to stop wrestling—even though the company needed him to tour. Instead of taking a break like 'Taker, Rey went on tour, further aggravating the injury while supporting the company. As a reward for his commitment to the job, WWE gave him the opportunity to run a program with anyone of his choosing (since he wasn't in a major storyline at the time). He chose Cody Rhodes—and helped elevate Rhodes to near-main-eventer status based on the strength of their impromptu program.
While this wasn't televised, a face-off between Rey and fellow high-flying luchadore Sin Cara actually occurred during a battle royal. This was something that everyone has been wanting to see since Sin Cara debuted on WWE. This delivered. Everyone in the ring completely stopped to watch the incredible moves the two were pulling off. Kofi Kingston's reactions said it all.
...until The Miz threw Sin Cara over the top rope to a wall of booing.
Not long after the above event, WWE made the decision to pair Rey and Sin Cara together and unleash them on the new-look Tag Team division. The HSQ is predictably through the roof.
In his WWE Championship match with John Cena, it looked like Cena was going to go for the STF, only for Rey to quickly get out of it and put the STF on Cena. Sure, Cena managed to get out of it ( and ultimately win) but this was something we'd never seen from Rey before. And it was awesome.