Here is the full list of all 12 Karateka achievements.
Rescued Mariko as the Monk
Defeated Akuma without collecting any of Mariko's flowers
You reached the Bamboo Forest in under 6 minutes
Rescued Mariko in under 30 minutes
Rescued Mariko from the evil warlord Akuma
Reached the palace gates
Earned the respect of a brother monk
Reached the palace garden
Defeated the bully on the bridge
Rescued Mariko as the True Love
Surmounted the Great Wall without getting hit once
Challenged Akuma, untouched by his minions