Friendship Games out of Water

This idea begs the unasked question, "What if Sponge out of Water & Friendship Games were released at the same summer day (June 19, 2015 [for America, at least]) in 1 movie?".

Plot
After the discussion of an incident where Sunset Shimmer chases after a rather familiar-looking mysterious hooded girl scanning the CHS statue, the story suddenly shifts as a book read by a pirate known as Burger Beard, reading about the endless fights between The Krusty Krab & long-time rival The Chum Bucket due to the former's secret formula for their top menu item, the Krabby Patty. One time, however, the formula disappears just as Plankton, owner of The Chum Bucket, tries to take away the formula from SpongeBob, fry cook of The Krusty Krab. Plankton is chased by The Krusty Krab's customers, but is saved by SpongeBob, who was with him when the incident happened. Soon, Bikini Bottom degraded into an apocalyptic wasteland, with everyone but Karen, Plankton's wife, turning on him & SpongeBob. Burger Beard ends the story there, but the listening seagulls want it to continue, & in a fight, rip off the page with "The End!" written on it as a seagull throws it in the ocean.

Back at CHS, a pep rally takes place, and Rainbow Dash suddenly "ponys up" without her guitar shortly after. Vice Principal Luna tells them to ensure they don't use their magic as to not cheat. Sunset is tasked with investigating her friends' magic, & writes a letter about it to Princess Twilight Sparkle. Meanwhile, the Twilight Sparkle of the human world is convinced by Principal Cinch to join the Shadowbolts to compete with CHS, with the reward of applying for Everton. While that's all happening, SpongeBob & Plankton unsuccessfully get their friends to help them. Luckily, Karen was still loyal to Plankton, so with her help, they travel back in time to retrieve the formula before it disappeared. In their quest, one of their destinations was in the middle of space, where they meet Bubbles, who attacks them after the duo screw up with watching Saturn & Jupiter while he took a bathroom break, with the fear of being fired. They escape before he could hurt them any further. Burger Beard, back on shore, with the formula in hand, starts his own food business & makes the seagulls flee with hot wings.

Crystal Prep is welcomed into CHS, where Sci-Twi meets the Rainbooms, & is confused when she finds out they know her. Pinkie clarifies that the Twilight they're meeting is the Twilight from this world, also considering she looks different. Her amulet causes problems, however, as the portal to Equestria is rendered useless. Back under the sea, Sandy tells everyone of her conspiracy theory when SpongeBob & Plankton return with the formula, but turns out, they accidentally grabbed Plankton's decoy instead, which was a hate letter from him. The townsfolk plan to sacrifice them, with Plankton baselessly blaming SpongeBob, who suffers a breakdown until he stops. After coming to, SpongeBob then volunteers to be sacrificed, but they smell Krabby Patties before they can go through with it.

SpongeBob, Plankton (hiding in one of SpongeBob's socks), Mr. Krabs, Patrick, Squidward, Sandy, & Gary all go oversea, & with the help of Bubbles (who was actually sick of his job), gain the ability to breathe in land. Once they emerge from a sand castle, they're smacked away by a little boy, all the way to CHS, where they meet the Rainbooms & Shadowcolts. That's when Pinkie Pie starts a welcoming party for Crystal Prep & the Bikini Bottom crew. However, when Pinkie ponys up, Sci-Twi's amulet takes her magic away. Principal Cinch then gives a speech rather arrogantly on how Crystal Prep will win the games once again, which is proven later on.

Later, Sci-Twi accidentally drains Fluttershy's magic, & soon after a Equestrian jackalope appears gives Spike the ability to talk. As the Friendship Games continue, an argument between Sunset & Sci-Twi ensues after Rainbow Dash's magic is taken from her. But at the same time, SpongeBob & crew find Burger Beard, who banishes them all to Pelican Island with his book. At the final event of the Friendship Games, Sci-Twi is forced to unleash their magic for them to win, transforming into Midnight Sparkle. Burger Beard is also there too as a sponsor selling Krabby Patties. But by then, SpongeBob & friends return as superheroes, unwittingly leaving Plankton behind.

After confronting Midnight Sparkle, Sunset restores everyone's magic & becomes Daydream Shimmer, & while she battles Midnight, our aquatic superheroes take on Burger Beard, with help from the Rainbooms. Daydream successfully defeats Midnight, but the former also gives her her hand, which she accepts. They then decide to go after the plunderous pirate as well. But even when they come to help, Burger Beard proves too powerful for them, & gets away with the formula. However, before he leaves, he is stopped by Plankton, now a muscular superhero known as PlankTON. The pirate splatters hot sauce on his eye & tries leaving, but everyone uses their powers to stop him. He is especially disoriented by PlankTON, who, together with SpongeBob/Invincibubble blows into the latter's bubble wand, enrapturing Burger Beard in a wave of bubbles. Once the formula is retrieved, PlankTON kicks Burger Beard all the way to Bikini Atoll. The former gives back the formula to Mr. Krabs, as they celebrate with the games ending in a tie, our heroes putting their hands in the middle, Sci-Twi enrolling for CHS instead, & Invincibubble singing.

They have an outdoor picnic shortly after, but that's when Princess Twilight FINALLY arrives, meeting her counterpart, SpongeBob, & his friends. Once all is settled, the latter group says goodbye to CHS & returned to Bikini Bottom, where things go back to normal, including Plankton reverting back as Mr. Krabs' rival. After being turned down earlier, Burger Beard & the seagulls sing the SpongeBob theme song, with Bubbles interrupting with a rap battle before they finish. As the credits roll, pictures of the people at CHS & our undersea heroes spending good times together, as well as the latter group dancing to a mashup of "Right There in Front of Me" & "Squeeze Me". After the credits have finished rolling, SpongeBob's pet snail Gary continues chasing Plankton like he did earlier.

Cast

 * Tom Kenny - SpongeBob (past & present versions), Gary, Frenchy, Agreeable Mob Member, Waffle
 * Rebecca Shoichet - Sunset Shimmer, Sci-Twi (singing voice)
 * Doug Lawrence - Plankton (past, present, & robot versions), News Anchor Fish, Mob Member
 * Tara Strong - Sci-Twi, Twilight Sparkle
 * Antonio Banderas - Burger Beard
 * Clancy Brown - Mr. Krabs
 * Ashleigh Ball - Rainbow Dash, Applejack
 * Bill Fagerbakke - Patrick (present & future versions), Male Fish, Eager Customer
 * Rodger Bumpass - Squidward, Doctor Gill Gilliam, Angry Mob Member #2, Doughnut, Squidasaurus Rex
 * Andrea Libman - Pinkie Pie, Fluttershy, Sweetie Drops
 * Tabitha St. Germain - Rarity, Vice Principal Luna, Derpy
 * Cathy Weseluck - Spike
 * Iris Quinn - Prinicipal Cinch
 * Carolyn Lawrence - Sandy
 * Eric Bauza, Tim Conway, Eddie Deezen, Rob Paulsen, April Stewart, Cree Summer, Billy West - Seagulls
 * Matt Berry - Bubbles
 * Sienna Bohn - Sugarcoat
 * Sharon Alexander - Sour Sweet
 * Kelly Sheridan - Indigo Zap
 * Britt Irvin - Sunny Flare
 * Shannon Chan-Kent - Lemon Zest, Pinkie Pie (singing voice)
 * Nicole Oliver - Prinicipal Celestia
 * Britt McKillip - Dean Cadence
 * Jill Talley - Karen, Shubie, Ice Cream Cone #2
 * Paul Tibbitt - Kyle, Helpful Angry Mob Member, Himself
 * Andrew Francis - Shining Armor
 * Vincent Tong - Flash Sentry, Bus Driver
 * Dee Bradley Baker - Perch Perkins, Sandals, Customer #1, Fish on Bubble, Angry Fish, Maple Syrup Jar, Waffle, Ice Cream Cone #1, Furballs, Giant Cute Kitty, Rainbow, Spotlight Guard, Angry Guard #1, Tough Mob Member
 * Kevin Michael Richardson - Andy
 * Lori Alan - Pearl
 * Kazumi Evans - Rarity (singing voice)
 * Carlos Alazraqui - Seagull, Dead Parrot
 * Nolan North - Seagull, Dead Parrot, Pigeon Cabbie
 * Pat Pinney - Painty
 * Nice Peter - Surfer Dude #1, Seagull, Painty (rap voice)
 * Epic Lloyd - Surfer Dude #2, Seagull
 * Stephen Hillenburg - Himself, Baby on Stroller
 * Lillian Ellen Jones - Sandcastle Girl
 * Riki Lindhome - Popsicle #1
 * Kate Micucci - Popsicle #2
 * Brody Rose - Kicking Boy
 * Mary Jo Catlett - Mrs. Puff
 * Sirena Irwin - Computer Voice, Shocked Mob Member
 * Thomas F. Wilson - Angry Customer #1
 * Mark Fite - Customer #2
 * John Brown - Food Truck Patron
 * David Dickson - Man Eating Krabby Patty

Songs

 * Friendship Games
 * performed by Rebecca Shoichet, Ashleigh Ball, Andrea Libman, Shannon Chan-Kent, & Kazumi Evans
 * composed by Daniel Ingram
 * Thank Gosh it's Monday
 * performed by Tom Kenny, Bill Fagerbakke, & Clancy Brown
 * composed by Tom Kenny, Deborah Lurie, & Eban Schletter
 * CHS Rally
 * performed by Ashleigh Ball
 * composed by Daniel Ingram
 * What More is Out There?
 * performed by Rebecca Shoichet
 * composed by Daniel Ingram
 * Teamwork
 * performed by Tom Kenny & Doug Lawrence
 * composed by Riki Lindhome & Kate Micucci
 * Squeeze Me - N.E.R.D.
 * The Music in my Mind
 * performed by Tom Kenny, Bill Fagerbakke, Clancy Brown, Rodger Bumpass, Carolyn Lawrence, & Doug Lawrence
 * composed by Daniel Ingram
 * I Hate People
 * performed by Rodger Bumpass
 * composed by Kaz, Rodger Bumpass
 * ACADECA
 * performed by Rebecca Shoichet & Tom Kenny
 * composed by Daniel Ingram
 * Unleash the Magic
 * performed by Iris Quinn & Rebecca Shoichet
 * composed by Daniel Ingram
 * Best Day Ever
 * performed by Tom Kenny, Rebecca Shoichet, & Ethan Slater
 * composed by Tom Kenny & Andy Paley
 * SpongeBob SquarePants Theme Song
 * performed by Pat Pinney, Devin & Caryn Johnson, Sara Paxton, Camryn Walling, Harrison Fahn, & Elan Garfias
 * composed by Hank Smith
 * Rap Battle
 * performed by Matt Berry, ERB, & Pat Pinney
 * composed by Peter Shukoff & Lloyd Ahlquist
 * Squeeze Right in Front of Me
 * performed by Rebecca Shoichet, N.E.R.D., Tom Kenny, Doug Lawrence, Ashleigh Ball, Andrea Libman, Shannon Chan-Kent, Bill Fagerbakke, Clancy Brown, Rodger Bumpass, Kazumi Evans, & Carolyn Lawrence
 * composed by Daniel Ingram & N.E.R.D.
 * Patrick Star - N.E.R.D.
 * Sandy Squirrel - N.E.R.D.

Trivia

 * Executive producer Stephen Hillenburg said that this was neither really part of the SpongeBob movie series or Equestria Girls TV-movie series, but the events in this movie do happen in both continuities.
 * No SpongeBob character, including the ones introduced in this movie, were seen in trailers, nor hinted by any of the crew in order to keep their appearances secret. They were only revealed in future TV spots 1 day after the movie released in America.
 * This movie was released in America first to avoid other countries spoiling that SpongeBob characters were in the movie online.

Other links

 * Friendship Games out of Water/Transcript