Some people are having issues with this unlocking. It may not work if you learn the skills from Kinarhi’s rivals.
This achievement is awarded for unlocking all the Overdrive Techniques for Kimari.
He starts with Jump and you must learn the following 11 from certain enemies.Technique - Enemy
Seed Cannon - Ragora (A tutorial guides you for this)
Thrust Kick - YKT-63, YKT-11
Aqua Breath - Chimera, Chimera Brain
White Wind - Dark Flan
Mighty Guard - Behemoth, Behemoth King
Fire Breath - Dual Horn, Valaha, Grendel
Self-Destruct - Bomb, Grenade
Stone Breath - Basilisk, Anacondaur
Doom - Ghost, Wraith
Bad Breath - Malboro, Great Malboro
Nova - Omega Weapon, Nemesis
In order to learn the attack, when facing one of the above enemies, use the Lancet ability which you can find under Special when in the attack menu.
Later in the game you can also learn many of these from Kimarhi's rivals -