Eyeshield 21 - Max Devil Power - Platform: Nintendo DS

Kyoshin Poseidon characters and uniforms:
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Successfully complete Story mode with the Game Boy Advance game
Eyeshield 21: Devilbats Devildays in the cartridge slot to unlock
Kengo Mizumachi and Shun Kakei. To use Kyoshin Poseidon uniforms,
hold L while choosing an edit team with Shun and Kengo in it. 

NASA Aliens team:
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Successfully complete Story mode, then the NASA Aliens team will
challenge you. Defeat them to unlock them as a selectable team.