The flashback of when Wario tried to introduce Kirby as a potential third team mate to Bowser.
The Imagine Spot Wario has after Bowser temporarily ascends to godhood.
Cool and Unusual Punishment: It hasn't been revealed yet as to which it is, but Mewtwo's "Merry-go-Round" or "Carousel" are usually used as a threat to Bowser for one reason or another during his mentorship.
Crowning Music of Awesome: The title theme since around episode 7 or so is the second opening theme of Digimon Savers, "Hirari." Some the more recent episodes either use part of the full verison of the song or even use a Fan Dub version. The closing themes are nothing to sneeze at either.
Doing It for the Art: Machinima is never made with profit in mind. Tigura21 also refuses to put Smash King on Machinima.com's YouTube channel, pretty much the only way to actually make money with machinima, due to not wanting to lower the quality of the series by adhering to Machinima.com's rules.
Epileptic Trees: Since reincarnation is one of the many overarching themes in the series, many fans believe that Wario is a reincarnated Pichu. The evidence: both are perverts and also Bowser's best friend.
When given the fact that the Creator's Triune is comprised of trophies fought in the Event challenges, some believe that Mario, Sonic, and Snake are part of their own Triune, given that all three are fought in the final event mode of Brawl.
During Wonders of the Miiverse, Samus and Peach decide to file a complaint with Dedede following several sexualized posts about the former. With the Miiverse service shutting down in 2017 (thereby eliminating the stage's main gimmick), it appears they succeeded.
Early on in the series, Ganondorf references his design shift from Melee to Brawl by commenting about getting a facelift. Come Super Smash Bros. Ultimate, and Ganondorf is reverted to his appearance from Ocarina of Time, effectively undoing his makeover.
Episode 19 centered heavily upon Ridley's upbringing as the "next generation" of villains known as the "Tetra Cardinals" and his newfound presence among the characters, including the murder of Samus. Only a few weeks later, Ridley was revealed as a playable newcomer to the next generation of Smash Bros, Smash Bros Ultimate, and similar to Smash King, his introduction began with wanton murder of characters.
Link: (to himself) Sorry Ike, but I've gotten far too comfortable with who I am now. I'm too far gone. And if that's going to be a problem, you'll just have to kill me. Maybe the Link after I'm gone will be more of your standards.
Schedule Slip: Justified in that, according to Word of God, most of the episodes were edited on outdated hardware and software:
The Reunion Special, Christmas Special, the double episode release.
Episode 17: Part 1 came out in October of 2013, Part 2 in December 2014, and Part 3 on January 31st, 2015.
The Episode 4 remake: Part 1 came in out April 2015, with the remaining two parts coming out in Fall 2016.
Racconto: File 5 was uploaded in 2014. Although File 3 is confirmed to be the next one, there hasn't been any word on it since Episode 17's completion in 2015.
Both Episode Lucario and Episode Bowser remain at just one part since 2015 and 2016, respectively.
The Woobie: Some of his backstory depicts Bowser as this. Happens in the main story as well.
As of Smash King HD, Ridley seems to fall into this to a much lesser extent than Bowser. He's smitten for Lizardon, despite her and Bowser screwing with him on a daily basis. The way he desperately attempts to hit on her as she hangs up kinda makes you feel sorry for the poor guy.