Metalions

The series ran 4 seasons across 104 episodes and has finished, so there is no cliffhanger risk.

While cleaning his house, eight-year-old Elon finds a summoning device and scooter left behind by his brilliant scientist grandfather. While riding the scooter and wearing the summoning device on his wrist he gets into a dangerous situation. Just then, the Archean necklace his grandfather left behind starts lighting up and summons an ancient Infinite Warrior (a Metalion) named Leo. Leo saves Elon from danger, and develops a liking for Elon. The newly reawakened Leo is appalled by the unruliness of humans and is saddened that Earth’s energy had long been depleted. Leo explains to Elon how he’s a Infinite Warrior and used to be his grandfather’s friend. Leo asks Elon to help him find all the remaining Archean Stones to restore the Earth’s energy. Elon designs a stone detector and uses it to begin his journey with Leo. The pair set off in search of the stones scattered around the world.