I think Killer Croc and Jinbe would have a really unique interaction. Given that they are both sort of 'fish - like' in their own ways. Jinbe might be initially cautious around Killer Croc because of his more menacing appearance, but then they could bond over their shared strength and their experiences in the water - based environments of their respective worlds.
The interaction between Naruto and Luffy would be really interesting. Luffy is carefree and impulsive, while Naruto is more about determination and protecting his friends. They could learn a lot from each other. For instance, Luffy could teach Naruto about having more fun in their adventures, while Naruto could show Luffy how to be more strategic in battles.
Another interesting interaction could be between Gwen (from Ben 10) and Nami (from One Piece). Gwen's intelligence and magical abilities would contrast with Nami's skills in navigation and her love for treasure. They could exchange knowledge, with Gwen teaching Nami some basic magic spells in exchange for Nami teaching Gwen about navigation techniques across the Grand Line.
Sasuke and Zoro could have some cool interactions. They are both very strong and somewhat brooding characters. Zoro might be interested in Sasuke's Sharingan and the power it holds, while Sasuke could be intrigued by Zoro's three - sword style.
I think Luffy and Spider - Man would be really interesting. Luffy with his carefree and fearless nature, and Spider - Man with his witty remarks. They would probably get along well and have some crazy adventures together.
Zoro and Vegeta would also have a great interaction. Zoro, with his strong sense of honor and his goal of becoming the world's greatest swordsman, would be a worthy opponent for Vegeta. Vegeta would be interested in Zoro's swordsmanship and might even see him as a potential rival. They could have some intense training sessions together, sharing their knowledge of combat and power - up techniques.
Well, a plot could be that the Marines in One Piece decide they need some extra help to deal with the pirates, so they make a deal with Amanda Waller to bring in the Suicide Squad. But the Suicide Squad has their own motives and end up causing chaos. For example, Harley Quinn might befriend some of the wackier characters in One Piece like Buggy the Clown, and they start their own little misadventures while the rest of the team tries to figure out how to get back to their own world.
Deadpool, without a doubt. His crazy antics, fourth - wall - breaking, and unpredictable nature would add a whole new level of chaos to the already volatile Suicide Squad. He would constantly be making jokes, getting into fights with the other members just for the fun of it, and finding unique ways to solve problems that the more traditional Squad members wouldn't think of.
Definitely Naruto and Luffy. Luffy is carefree and impulsive, while Naruto is also quite headstrong but has a strong sense of justice. Their interactions would be hilarious as they might not understand each other's worlds at first. For example, Luffy might be confused about Naruto's chakra and ninja tools, and Naruto might be shocked by Luffy's rubber body. Another interesting interaction could be between Naruto and Zoro. Zoro's serious and dedicated nature towards his swordsmanship could contrast with Naruto's more energetic and sometimes goofy nature.
One interesting pairing could be Edward and Deadshot. Edward's ability to read minds could be really useful in helping Deadshot with his aiming. Deadshot, on the other hand, could teach Edward about human combat techniques that the vampires might not be familiar with.
Goku and Luffy would be really interesting. Goku is all about pure strength and the pursuit of becoming stronger through training, while Luffy is more about the adventure and his dreams. Their different outlooks could lead to some great conversations and also some funny moments, like when Luffy tries to eat Goku's senzu beans thinking they are some kind of food from his world. Another interesting interaction could be between Vegeta and Zoro. Vegeta is very proud and serious, and Zoro is a swordsman with his own code of honor. They could have some intense sparring sessions and also respect each other's strength.