The police need to be involved. They should start an immediate investigation, following any leads like eyewitness accounts or ransom demands.
One reason could be for ransom. Gangs might think the family can pay a large sum of money. Another reason is to use the kid in their illegal activities like drug trafficking. They may force the kid to be a lookout or a courier.
First, call for an ambulance immediately. Then, if there are bystanders, they should not move the two casually to avoid further harm. Wait for the medical professionals who are trained to handle such situations.
His friends could use their various quirks to track him. For example, if there are characters with enhanced sense of smell or the ability to detect energy, they could start the search. Then, they would plan a strategic attack on the kidnappers' hideout.
Dean and Cas could use their combined skills. Dean's hunting expertise and Cas's angelic powers would be a great asset. They might track down the kidnappers through some supernatural means like following a magical trail or using Cas's ability to sense Sam's location.
The other Teen Titans could also play a big role in the rescue. Starfire could use her powers to fly in and distract Slade while Cyborg and Beast Boy create a diversion. Raven could use her magic to break any spells or traps that Slade has set for Robin. They would all work together as a team to get Robin back safely.
One way could be a stealth mission. Shikamaru, with his high intelligence, could plan a strategy to infiltrate Kumo's hideout undetected. He could gather a small team of skilled ninja like Neji (if he were still alive in the fanfiction), Rock Lee, and Ino for mind - reading and communication. Then they could free Naruto and Hinata and escape before Kumo realizes what's happening.
Joel could use his combat skills and stealth to infiltrate the place where Tess is being held. He'd probably take out the guards one by one and then free Tess.
The Sailor Guardians could start by using their powers together. Sailor Moon could use her Moon Healing Escalation to try and sense any dark energy around where Michiru was last seen. They could also split up and search different areas. Maybe Neptune's own powers could be used in some way to call out to her or track her down. Once they find the location, they would fight off the kidnappers using their combined attacks.
Yusuke could use his spirit detective skills to track down Keiko. He might fight his way through Sakyo and Toguro's minions to reach her.
The Wild Kratts team could use their animal powers to rescue Martin. For instance, if they had the power of eagles, they could fly over the area where he might be held and look for any signs of him.