Most enemies you fight in this game are wildlife or no-name soldiers. Before you get to fight him, you have to complete tasks that are - objectively - rather boring, ranging from picking flowers to rescuing people. Here you have Goku, tournament winner and the world's strongest, who has protected Earth from Piccolo Jr and now his son has been kidnapped by his evil brother Raditz. While that sounds cool and all, this game has been implemented rather poorly.
As Goku, you fight enemies or accomplish certain tasks to become stronger and go on to protect the universe from the evil Frieza. The game covers the Saiyan and Namek arcs of the Dragonball Z manga/anime.