How about a crossover with Sonic the Hedgehog? Picture this: Sonic is running through a strange new zone and accidentally enters Joe's world. They join forces to stop Dr. Eggman who has somehow teamed up with one of Joe's enemies. Sonic's speed and Joe's Viewtiful powers would create a really fast - paced and exciting story.
A great plot could involve a powerful enemy that has the ability to drain the 'viewtiful' energy from Joe. Tsukune and his friends notice the weakened Joe and decide to help. They all train together, combining their different powers and skills. The story could then build up to an epic showdown where they all have to use their combined strength to defeat the enemy and Joe regains his full 'viewtiful' power.
Inklings from Splatoon could also be fun to include. The Inklings' ink - based attacks and their unique culture could add a new dimension to the story. They could team up with Joe to stop an enemy that is trying to cover both their worlds in some sort of dark, gooey substance. Joe would have to figure out how to work with the Inklings' different combat style.
One creative plot twist could be that Viewtiful Joe's VFX powers start to malfunction in the School DxD world. This could lead to all kinds of chaos as he tries to control his powers while dealing with the devils and other supernatural beings in School DxD. Another could be that the characters from School DxD gain some of Joe's powers temporarily and have to learn how to use them in their own battles, which would completely change their fighting styles.
The interaction between Viewtiful Joe and Moka would be really interesting. Moka's vampire powers and Joe's 'viewtiful' abilities could create some really cool fight scenes. Also, their different personalities - Moka's shy - vampiric duality and Joe's confident heroism - would make for some great dialogue and character development moments.
Joe would probably be very confused at first in the School DxD world. He's used to his own kind of battles, and suddenly being in a world full of devils, angels, and other mythical creatures would be a shock. He might be very cautious and try to figure out who the good guys and bad guys are. The devils in School DxD might be intrigued by Joe's powers and either try to recruit him or study him. The angels, on the other hand, might be more suspicious and see him as a potential threat at first.
Another interesting concept is a character - based crossover. A Joe like Snake Eyes could form an unlikely bond with a Transformer like Bumblebee. Snake Eyes' ninja skills could be used in combination with Bumblebee's speed and agility in combat. They might start off not trusting each other but gradually learn to work together as they face various threats.
One idea could be Joe Lawyer taking on a high - profile case against a powerful corporation. He discovers some deep - seated corruption within the company and has to fight against various threats to expose the truth.
One idea could be to have Snake Eyes cross over into a modern urban setting where he has to use his ninja skills to fight a new kind of crime syndicate. Maybe he teams up with a local detective who is initially skeptical of his methods.
One plot idea could be Quinn and Joe collaborating on a musical project for Glee club. They might have different styles at first, but as they work together, they learn from each other and grow closer.
One idea could be an OC who is a skilled mechanic in Immortan Joe's world. This OC could secretly be working on a vehicle that has the potential to outrun all of Joe's war machines, aiming to use it to escape the tyranny. Another plot could involve an OC who is a healer and tries to find a way to cure the diseases that plague the people under Immortan Joe's rule. Or perhaps an OC who is a spy from another tribe, sent to gather information about Joe's weaknesses.