The Clone Marine Corps are the best trained of the Republic's Military. They are considered the best due to their training phases, including: Marksmanship, Conditioning and Martial Arts. Clone Marines are famous for upon a time tearing apart 100 Droid Marines and 210 Super Battle Droids with their bare hands.
Conditioning: Clones are told to go through a series of battle simulation courses, obsticle courses, Military calmness and Military tactics.
Marksmanship: Clones are trained to shoot assault rifles, rocket launchers, sniper rifle, pistols and long range weapons at very far distances.
Martial Arts: Clones are trained to be black belts in Judo, Karate, Ti Kwan Du, Jiu Jitsu, Krav Maga, Wrestling and Kick Boxing.