Perhaps it's just me, but the very first thing shown is awesome: The Universal logo and theme in 8 bit!
Scott and Knives defeating Gideon through co-op mode, replicating the attacks from the Ninja game earlier in the movie.
Fueled (quite literally) by Awesome Music, the Sex Bob-Omb's electric yeti monster faces off against the Katayanagi Twins' Double Dragons.
Edgar Wright fans know there is a specific point in Hot Fuzz when an already funny movie suddenly became awesome. Scott Pilgrim vs. The World has a very similar "specific point", and that point is when Matthew Patel bursts through the ceiling, declares the beginning of the fight, and leaps at a confused Scott...who reacts by putting on a determined expression, throwing his guitar to Young Neil, blocking Patel, and punching him away, all with Written Sound Effects and a REVERSAL popup on the screen. It was at that point when all the Video Game Tropes that make this movie so unique started coming into play.
"We are Sex Bob-omb, and we are here to watch Scott Pilgrim kick your teeth in! ONE!TWO!THREE!FOUR!"
Katayanagi Twins: I'm sorry, but there isn't a moment here that isn't amazing.
Gideon Graves: Scott kicking security's collective ass with The Power of Love, Scott and Knives using Ninja Ninja Revolution moves to beat the crap out of Gideon, Ramona's "Let's both be girls." line.
Scott vs. Gideon with swords!
Ramona vs. Roxy, before Scott joins in. Particularly awesome is because this is pretty much the only time Ramona truly asserts herself, protecting her boyfriend, fighting offensively, and openly defying the Evil Exes rather than being a Neutral Female.