This is an older anime
Season 1
The story starts out with the Battle of the Supernatural Powers, a tournament to decide who will be the next god of The Celestial World (rendered as God Candidates.
Each candidate (100 in total) is required to choose a junior high school student to act as their fighter. The student is given a unique power and told to eliminate as many enemies as possible. The winning God Candidate will become The New God of Heaven and the winning student will receive the Blank Zai (or talent), a talent that can be anything they choose.
While this leads many students to thoughts of greed and selfishness, Kosuke Ueki decides to take it upon himself to win this tournament to keep that power away from those that would abuse such a gift.
The Law of Ueki Plus
Season 2
Two years after the tournament in The Law of Ueki, Kosuke Ueki is now a 3rd year student in Hinokuni Junior High School. For some reason, everyone in the real world has lost their memory of their most important person, including his friends who participated in the tournament two years ago. Ueki is the only one unaffected, and is fighting in order to restore everyone's memories. He follows a little sheep named U-lu (wool in English) to another world called Hangekai where he meets new companions and gains new abilities.