During Rainbow's Test of Bravery, Peter manages to knock out a dragon with a single kick of his hind legs. Rainbow's jaw drop is quite fitting.
Also when he saves Zecora from a Hydra.
Princess Luna coming to Peter's aid when he was about to get killed by Discord's dragon lackey.
The fact that Spider-Mane is able to keep up with Spitfire, during a race through Manehattan is quite impressive.
Peter stopping an airship in Manehattan from crashing on the streets, during the race.
When King Sombra gets easily beaten by Pete.
Spider-Mane's duel with Princess Luna, ends with an unexpected One-Hit Kill.
To be fair, it was because she understimated him at the time, according to Celestia. If she hadn't, the fight would have probably been more challenging.
And on top of that, his duel with Princess Celestia herself! Even though he was holding back considerably, Peter still fought with such speed that spectators like Twilight had to magically enhance their vision just to be able to track his and Celestia's movements! Not only that, but he broke Celestia's war-glaive, Ignus Solaris, a sword forged from magic and the fire of the sun! He also forced Celestia into expending a large amount of her magical energy, just to incapacitate him, leaving her considerably winded. Celestia even admits, for the day, he had proven himself her better in combat. And all of it set to the tune of "Rising Sun".
Peter's ceremony during the coronation party, where he ascends to knighthood and gains royal status.
Hey, remember Starswirl's time travel spell? The one that nearly drove Twilight bonkers that one time? She's weaponized it.
Pretty much the whole fight between Twilight and Sunset Shimmer when they arrive in the Marvel Universe.
And soon after that, Twilight defeating Hulk by using the Harmony beam.
Also, Spider-Man and Spike surviving a fight with Hulk until she was ready with the Harmony Beam.
There's also the time Peter and Spike were duking it out with Osborn's robots.
From Chapter 49, three words that many a Spider-Man fan has longed to hear after Twilight buys out the Daily Bugle and starts a campaign to clear Spider-Man's name of the years of mudslinging he's suffered from them: "Jameson, you're fired."
The very fact Spidey got in Equestria in the first place. Twilight Sparkle's spell was to summon the greatest hero in history. Let's this sink for a moment.
And then, when seeing his memories, Twilight discovers why: he once had all the power of the Infinity Gauntlet, he could do anything to all universes with it, he just needed to wish... And so he wished the whole adventure never happened and nobody would ever find the Gauntlet again. With that simple gesture, he saved all universes. And he didn't think much of it.
Applebloom deducing Spider Mane's identity with nothing more than logic and common sense.