Maybe the villains from Power Rangers Lightspeed Rescue find a way to enter the Naruto universe. The Rangers follow them and team up with Naruto and his friends. They could teach each other their fighting techniques. The Rangers could show Naruto how to use their high - tech weapons, while Naruto could teach them about chakra and ninjutsu.
Another concept could be that a character from the Naruto world, like Sasuke, is somehow transported to the world of Power Rangers Lightspeed Rescue. He has to adapt to the new environment and the different power system. He could start off as a loner but gradually learn to work with the Rangers to face a common enemy.