>>105842120Two very popular series that came out around the same time and had some similarities like the MC being a 12-year-old boy with a cheerful disposition hiding a conflicted history who wore bright clothes, had abilities associated with the wind and possessed a violent inner power that awoke in times of turmoil. The MC was associated with a brooding teenager that had fire powers and was descended from a family of exceptional status, who also had deep-seated issues that fueled an obsessive desire to fulfill their goals. The teenager is tutored by a hardened warrior of high rank with knowledge of useful techniques that the teen masters, the warrior possesses a laid-back and easygoing nature that masks their true potential.
Another companion was a girl that occasionally acted as a foil to the MC and searched for ways to achieve greater strength and power so as not to burden the team, learning healing techniques along the way (Naruto and Avatar's healing powers are based on the same real-world concept of Reiki).
The MC is also a chosen one tasked with bringing balance to their violent worlds, who must tame their inner powers to do so and sometimes prefer to use diplomacy to solve their issues. Their worlds make use of elemental magic and martial arts in battle.
These are pretty surface-level similarities that fall apart if you dig a little deeper, but they were good enough to promote a lot of crossover material, especially during both series' heydays.