Starhunter is an alien tribe that steals all life energy on other planets, gathering the energy in the sixth dimension using "King Medal" and bringing it under their control. Soon they created "Knight Medal" when "King Medal" was not able to absorb all the energy. Hoping to conquer the Earth in one fell swoop, since they believed it would not offer much resistance, they brought along both medals. Fortunately, the ship carrying both medals got hit by crossfire in a war that was going on down on Earth. The medals were lost as the ship exploded in Siberia. Starhunter was forced to retreat and create new medals.
One of the medals was broken into 5 pieces. The broken medal was taken by researchers headed by Dr. Earth, and the complete medal was taken by Dr. Heart. One day, Heart's research lab exploded and the medal was nowhere to be found. Later Dr. Earth realized that monsters that had begun to appear were humans that had absorbed the energy from the missing medal when the lab exploded.
Upon further research, Dr. Earth created "SportDetector" to control the 5 broken pieces and special suits to utilize each piece's unique power. He gave five youngsters the suits to stop these monsters.
Meanwhile, Starhunter is preparing their new invasion of Earth.
- By The Power Of Grey Skull: "Sport charge up! Change!"
- Combination Attack: Star Gate Judgmentation
- Elemental Powers
- Heroic Sacrifice: At the end of episode 16, Ace, Up, and New sacrifice their lives to destroy Starhunter's castle on Earth, ending the season on a Downer Ending.
- Humongous Mecha: The Sport Robo.
- Combining Mecha: Spirit Fighters Lead (Red) + Brain (Yellow) + Heart (Green) + Strong (Blue) + Base (Pink) = Sport Robo
- I Know Madden Kombat: The bread-and-butter of the series.
- In the Name of the MoonAce: "The power of a determined fist!" Boxing Red!Up: "The power of wise creativity!" Soccer Yellow!New: "The power of an agile mind!" Tennis Green!Yu: "The power of surging water!" Swimming Blue!May: "The power of gentle vigor!" Gymnastics Pink!
- The Bus Came Back: Yu's actress is the only one to reprise her role in Season 2.
- Transformation Trinket: Sport Detector