Eyeshield 21: Max Devil Power
Successfully complete Eyeshield 21: Max Devil Power and have Eyeshield 21: Devilbats Devildays in the Game Boy Advance slot to unlock Kengo Mizumachi and Shun Kakei. You can also hold L while selecting a custom team with both Kengo Mizumachi and Shun Kakei in it to get the Kyoshin Poseidon uniforms.
NASA Aliens team
Successfully complete Story mode then win the NASA Aliens team challenge.
Strategy guides from GameFAQs