Sonic and SpongeBob: Heroes Unite

Sonic and SpongeBob: Heroes Unite is an upcoming American animated crossover film set between the universes of Sonic the Hedgehog and SpongeBob SquarePants. The film combines traditional animation with CGI.

Plot
As the film opens, we see Plankton at the Chum Bucket thinking of a plan to steal the Krabby Patty formula. He tries several times to get the formula but fails everytime.

The scene then cuts to the surface where Sonic and his friends are battling Doctor Eggman. The mad doctor has built a giant robot and it was rampaging through the city. Knuckles came up with idea to distract the robots by taking them head-on on the ground, while Sonic and Tails go up from above in the Tornado to disable a bomb that Eggman planted, and to hopefully bring down the robot. Sonic and Tails go on the Tornado and take off. Tails had fortunately made a stealth mode on the airplane was able to go invisible to avoid detection. When Tails and Sonic got close enough to Eggman's air fortress, Tails made the Tornado un-camouflage and fired a missile. Eggman, in the fortress ordered his robots to attack the Tornado with canon balls, which the duo manage to evade. After dodging enemy fire, Sonic and Tails jump from the Tornado and free-fall towards Eggman's fortress. The duo landed on the hull and fight their way through the troops stationed there. As Sonic and Tails make their way through the sky force, Knuckles finally joins them in taking down the rest of robots, as he had managed to find a way up there. After defeating a martial artist robot, Tails takes the opportunity to disable the bomb before Eggman drops it on the city as Sonic and Knuckles cover him. Tails successfully deactivates the bomb and places his own bomb in the control room that is set to go off in one minute. Tails ushered his friends to get out of the air force, and escaped before the timer went off.

A few hours later, Team Sonic gathers with Team Rose and the Chaotix Detective Agency to celebrate their victory. As Amy brings out the cake that she baked for Sonic. They were at a restaurant for the record. As Amy brings out a knife to cut slices for everyone, there is a sudden news report that a bridge exploded and that Doctor Eggman had stolen the Chaos Emeralds. Team Sonic quickly go the scene to investigate. When they arrive at the bride, a team of corrupt SWAT officers accuse them of being responsible. Tails and Knuckles tried to reason with the team as Sonic made snarky remarks towards them. This offends the officers and point their guns at Team Sonic. The team retreat, with the officers taking pursuit. Eventually, the team split up as they deem the officers cannot follow all of them. Tails and Knuckles go in the same direction and turn right, while Sonic continues going straight. The officers quickly catch Tails and Knuckles. Sonic turns back to save them. While he does this he is knocked in the head with a three-pound metal weight, which knocks him out cold. As Sonic regains consciousness, he discovers that the SWAT officers were on payroll with Dr. Eggman, and that he was in handcuffs. He also notices that Tails and Knuckles were on the opposite side of the room they were in. One of the officers release Tails from the cell he was locked in and his held at gunpoint. Seeing this, Sonic effortlessly breaks free from his handcuffs and take down all the officers in the room. Sonic also smashes the window cell Knuckles was trapped in.

Sonic helps Tails and Knuckles stand on their feet as they make their way out of the building. As soon as they step out of the building, Eggman is waiting for them in a new giant robot, powered by the Chaos Emeralds. Sonic and his team battle the robot, but are quickly overwhelmed by its power. Sonic then orders Tails to spin him and throw him as hard as he can to launch him to the heart of the robot, where the controls and Chaos Emeralds are located. Tails complies with this and launches Sonic to the heart, which Sonic pierces through with his spin attack. Sonic begins breaking and disabling the controls, which he battles more robots that were inside the robot. Sonic then sees the Chaos Emeralds on the left-hand side of the robot and runs to them. As he does this, Doctor Eggman appears and traps Sonic in Energy Beams. Eggman electrocutes Sonic as he begins powering up a robot-machine hybrid with a tractor beam, which will destroy both Sonic and the city. Refusing to let innocents get hurt, Sonic selflessly puts his own safety aside as he absorbs more of electricity as he charges a light speed attack. White orbs begin to surround Sonic as electricity appears to dissipate. Sonic's eyes then turn a different color as he releases the light speed attack, piercing through his electric prison, much to Eggman's shock. Sonic then destroys the tractor beam that sets off a massive explosion and causes a blackout. The machine and five of the Chaos Emeralds were sent flying into the ocean. Despite enduring the explosion close-range, Sonic was injured and unconscious. Tails and Knuckles carry Sonic away from the docs.

Bikini Bottom, night, SpongeBob and Gary were sleeping until they heard an explosion. SpongeBob goes outside and see a large robotic hand and some metallic rubble. With the help of Patrick, SpongeBob lifts the robot hand and finds a Chaos Emerald in a small container. SpongeBob and Patrick think it is a precious gem, while Squidward knew what it was. The other Chaos Emeralds were located at the Chum Bucket, Rock Bottom, Jellyfish Fields, and Sandy's Treedome. As four of Chaos Emeralds were turned into the scientists, they discovered what power it had. The Bikini Bottomites deemed that unfair as to why the scientists possessed such power while they did not. Plankton stole the emeralds soon enough. The townspeople were furious and attempted to steal the emeralds back. The whole town became a warzone in a matter of days. Sandy created an energy pad to detect strong readings, because unbeknownst to them Sandy had the Chaos Emeralds and created a replica with all the same wavelengths and power as a real one. Sandy enlisted the help of SpongeBob, Patrick, Squidward, and Mr. Krabs as they traveled to Rock Bottom to retrieve the emerald. As they navigate through the dark town, they see a neon sign where the Chaos Emerald was. Squidward grabs it and puts it in the bag they brought.

Meanwhile on the surface, Sonic is still recovering from his battle with Dr. Eggman, and Tails suggest that they go look for the Chaos Emeralds, but Sonic tells him that five of them sunk in the ocean. Amy then suggested that perhaps maybe that Tails can build a submarine for them all to fit so they can find the emeralds together, as the sea fox was too small for all of them to fit. Tails was open to the idea and began building a submarine, but used the Miles Electric to get a good estimate as to where exactly in the ocean all the emeralds were. Tails got a location, and even got a brief clip of what the emeralds were seeing. Tails saw SpongeBob and his friends and then proceeded to tell the others what he saw. Tails then went back to building the submarine.

Sandy then turned in all the Chaos Emeralds and figured out the origin location of the emeralds. She told them that they were from the surface and such powerful energy should belong to someone good and not fall into the wrong hands. The town reluctantly agreed after seeing all the madness they had caused. The town then make their way to the surface. When they finally make it near the surface, a large robotic hand snatched all the Chaos Emeralds away. It was Doctor Eggman, who had been searching for the emeralds since losing them. Eggman quickly retreated afterward. Needing to get the emeralds back, SpongeBob and his friends travel to above water, and try to track down Eggman. Sometime during their adventure they meet Sonic and his friends. They team up to stop Eggman, and prevent him from conquering the world.

Animation
The 2D hand-drawn animated sequences for the film were done in South Korea at Rough Draft Korea. The film combines traditional animation with computer-generated imagery (CGI), which was handled by Iloura VFX in Melbourn, Australia, to render the characters into 3D.

The animation used for Sonic's world was done by Marza Animation Planet in Tokyo, Japan. The film also contained a cut-paper stop-motion sequence which was animated in a small room at Celluloid Studios, in Denver, Colorado.