OK K.O.! Let's Be Heroes/Ho Yay

Considering the creator previously worked on Steven Universe, this was bound to happen.

General

 * Enid is canonically Bisexual, and according to Word of God, Red Action is Gay, Lord Boxman is Pansexual, Professor Venomous is Bisexual, and the rest of the Hue Troop are also LGBT+.
 * When Rad and K.O. find out who Enid's Parents are, Rad states that both her parents are hot.

Enid

 * In "We Messed Up", when Enid sees Mr. Gar has a picture of KO's mom when she was younger, she eagerly asks who the babe is. She gets embarrassed when K.O. reveals that the "babe" is his mom.
 * When Enid and K.O. are biking to Rad's house in "Hope This Flies", Enid's helmet has a peace sign sticker colored like the bisexual pride flag. Word of God confirms she's bisexual in a Reddit AMA.

Enid/Red Action

 * Character designer Matthieu Cousin drew an artwork of Enid and an early design of Red Action where Enid looks at Red in awe while blushing while they're in action.
 * In "You're Everybody's Sidekick", Enid gets noticeably flustered and blushes when K.O. asks why she follows Red Action on social media before ending up gushing about her.

K.O.: You know her?

Enid: No. I mean, not really. I see her around and follow her online a bit, it's like, you know, whatever. (laughs nervously) She's just so wild sometimes.


 * In "K.O.'s Video Channel", when Rad and Enid discovers that K.O. uploaded a video of them dancing and messing up, they were both embarrassed, but Enid took it the hardest when Red Action is one of the people who saw the video and commented on it.
 * In an artwork of Enid's room, which drawn by storyboard artist Stevie Borbolla, on the mirror of Enid's dresser there are four photographs taped to it, and the photo on the top is Red Action.
 * Mira Ong, one of the storyboard artists, posted a comic strip on twitter of Red (poorly) flirting with Enid.
 * In "Hope This Flies", Red Action picks Enid up from Rad's house and the two of them return together the next morning.
 * In "Super Black Friday", after Gar tells his staff that they should shut down the store for tonight and use their precious time to be around people they love, Rad decides call his parents to let them know he's coming home while Enid decides to text Red Action to see what's up.
 * All this leads up to the reveal in “Red Action 3: Grudgement Day” that Red and Enid have started dating sometime between episodes.

Rad/Raymond

 * In "Sibling Rivalry", when Raymond asks the Bodega team if they want their butts kicked:

Rad: Ha! Kick my butt? Please! (shows his butt to Raymond) My two-pack is touting a 12-pack!

Raymond: Impressive...


 * Rad and Raymond's dance battle from "Plaza Prom" has already spawned multiple slashfics and is dripping with Foe Yay and Getting Crap Past the Radar.
 * In "Let's Watch the Boxmore Show" Rad calls Raymond "handsome but pretentious snob".
 * The episode "Project Ray Way", Raymond and Rad are basically fighting to see who's hotter. Raymond has seen [1] and Rad has blushed at Raymond during their fashion battle.
 * To a lesser note, Raymond is shown wearing drag through the majority of the episode.

Nick/Joff

 * The duo's interactions largely portray their relationship and especially discussions as Like an Old Married Couple. The two are seen in so many romantic interactions together that they're heavily implied to be a Battle Couple.
 * Nick is noticeably touchy-feely with Joff. He slung his arm around his shoulders in "You're Everybody's Sidekick", and while in the background, his hand was in Joff's lower back at "Plaza Prom"
 * In "Plaza Prom", near the end of the episode where everyone is dancing, Nick Army and Joff can be seen holding each other's hands while they dance. It's also pretty clear through the episode that they're each others' dates.
 * In a short scene of "Second First Date", they are seen eating together by themselves on a spot where it's implied to be typically where couples go on dates.
 * Danny Ducker, one of the storyboard artists and writers for the show, posted three images for Valentine Days on Twitter and Tumblr, one of which includes Nick giving Joff a bouquet of grenades, while they both blush.
 * During "Plaza Film Festival" in Nick's film entry he plays a character who cries about how he hurts everyone with his grenade hands and how everyone thinks he's a monster, to which Joff's character lays on his chest and says that he doesn't.
 * In "Be A Team", Nick and Joff are tasked with giving team-building exercises to K.O., Rad, and Enid. Their first exercise is looking each other in the eyes and saying "I love you". At the end of the episode, they walk into the sunset holding hands.
 * In "Project Ray Way", both of them squee when Rad notices them during a fashion show
 * In "Thank You for Watching the Show", they're shown getting married.