"Me, Myself, and I" from "High School Sensation", especially with Cymphonique and Romeo performing together.
"Deck The Halls", How To Rock style.
Fan-Preferred Couple: Go look up How to Rock fanfiction and you will notice there are more Stevie/Zander fics than there are stars in the sky.
Fandom Rivalry: A bitter one with Sam & Cat after How To Rock's creator revealed that they were cancelled because of it.
Harsher in Hindsight: Kacey spent most of the series trying to stop and outdo Molly since being kicked out of the Perfs. She was able to beat Molly and get the last laugh many times, but their backstory in "How To Rock Christmas" reveals that this is exactly the type of behavior Kacey had towards Molly when she was queen of the Perfs and why Molly has such a grudge against her to begin with.
Incidentally, this recalls the plot of the books.
Hilarious in Hindsight: Zander dancing with Grace in "How to Rock a Secret Agent" becomes this after watching Series/Crisis, where Max Schneider's character has a crush on Halston Sage's character.
Les Yay: Let's just say that Kacie and Stevie have plenty of moments where they're really close with each other.
What an Idiot!: Molly in "How To Rock A Music Video." Where on Earth did she get the idea that Kacey would accept having to play personal assistant to her just to get back in The Perfs?