Here is the full list of all 20 No More Heroes achievements.
You have accomplished everything!
Sweeter than you thought? Just like Sylvia!
Collected 51 trading cards!
You have defeated "Henry"
You have defeated "Jeane"
You somehow managed to visit every bathroom in Santa Destroy. Why don't you start living in one?
Used whatever means available to beat 510 regular enemies
Finished all of Ryu's instructions! You wanted THAT!
Earned 10 Gold Medals on Free Fight Missions
Earned 20 Gold Medals on Assassination Missions
Earned 9 Gold Medals on part-time jobs
You have defeated the Rank 2 Assassin "Bad Girl"
You have defeated the Rank 3 Assassin "Speed Buster".
You have defeated the Rank 4 Assassin "Harvey Moiseiwitsch Volodarskii".
You have defeated the Rank 5 Assassin "Letz Shake".
You have defeated the Rank 6 Assassin "Holly Summers".
You have defeated the Rank 7 Assassin "Destroyman".
You have defeated the Rank 8 Assassin "Shinobu".
You have defeated the Rank 9 Assassin "Dr. Peace".
You have defeated the Rank 10 Assassin "Death Metal".