It could be really cool. Maybe Naruto and his friends could end up in the Ice Age world. They might use their ninja skills to help the Ice Age characters. For example, Naruto could use his shadow clone jutsu to gather food for the prehistoric animals more quickly.
A plot could involve a powerful jutsu in the Naruto universe accidentally creating a rift that leads to the Ice Age world. The Naruto characters then have to team up with the likes of Manny and Sid. For example, Sakura could use her medical ninjutsu to heal any injured animals. And in return, the Ice Age animals could show the Naruto gang how to survive in the harsh, cold environment.
Well, it could be that Naruto somehow gets transported to the Ice Age 2 world. Maybe he uses his ninja skills to help the animals there. For example, he could use his shadow clone jutsu to gather food more quickly for the starving animals during the ice age.
Manny from the Ice Age could be very interesting. In a crossover, he would be the big, strong and somewhat skeptical character towards the Naruto bunch. He has his own code of honor in protecting his herd, and seeing how he interacts with the ninja, especially with their strange powers like Naruto's Rasengan, would be really cool. He might start off not trusting them but eventually come to respect them.
Definitely Sakura and Sid. Sakura is a strong - willed and intelligent character. Sid is a bit of a goofball. Sakura could be constantly exasperated by Sid's antics, but at the same time, Sid could bring out a more fun - loving side of Sakura. And Sakura could use her medical ninjutsu to help Sid if he gets injured during their adventures in the Ice Age world.
I think Naruto and Manny would be an interesting combination. Manny is this big, strong mammoth, and Naruto is a skilled ninja. Their personalities are so different. Naruto is full of energy and always eager to prove himself, while Manny is more of a calm and protective leader. It would be fun to see how they interact and how Naruto's ninja skills might come in handy in the Ice Age world with Manny's brute strength.
Friendship could be a major theme. Characters from two different worlds, like Balto and Scrat from Ice Age, could form an unlikely friendship. Despite their differences in species and the worlds they come from, they find common ground and support each other.
Well, one possibility could be that the characters from Ice Age end up in the feudal Japan setting of Inuyasha. Sid could befriend Shippo, the fox demon. They might get into all sorts of comical situations together, like trying to find food in a world full of yokai. Manny, the mammoth, could be mistaken for a strange demon by some of the more superstitious villagers. And Diego might team up with Inuyasha to fight a common enemy, perhaps a powerful ice - based demon that threatens both their worlds.
Well, from other movies, Woody and Buzz from 'Toy Story' would be great. Woody's leadership and Buzz's bravery would add new dynamics to the Ice Age group. Also, Simba from 'The Lion King' could be interesting. His journey to become king could intersect with the Ice Age characters' journey in some way. And of course, Shrek would bring his own brand of humor and gruffness to the mix.
One idea could be a crossover with 'The Lion King'. The Ice Age characters could end up in the Pride Lands. Sid might make friends with Timon and Pumbaa, while Manny and Diego have to deal with the lions. Another could be a crossover with 'Finding Nemo'. The Ice Age gang could somehow find themselves in the ocean, trying to help Marlin find Nemo. It would be a really wacky and fun adventure.