In the wild, Metapod are only capable of using one technique, and that is Harden. Typically, when attacked by trainers or predators, they use this technique to make their exoskeleton even tougher and hope their foes will get tired of bothering them. If it survives this period, after a few months in this state it will evolve again into a Butterfree.
This is far too long a wait for most bug catchers' liking. For a trainer with a full roster, this wait is annoying but acceptable: for someone who started with a Caterpie, it is simply intolerable, and therefore it has become something of a rite of passage for young bug catchers to teach their Metapod to use Tackle.
This is never an easy task. Metapod, after all, not only lack limbs, but also the lithe body and slithering capability of snakes – and although some may see friends pull it off and figure it out, typically each trainer relearns the method together with their pokemon. Typically (for there are a hundred variations) Metapod rock back and forth on their unbalanced bodies, increasing their momentum until they can launch themselves forward by about a foot. It resembles a rollout more than a standard tackle and is a weak attack, good only for defeating pokemon half its level and wild Metapod.
Some have said that Metapod are an easy pokemon to train, for they only require three levels to evolve. Most bug catchers would retort that it's easier to train a Pidgey ten levels than a Metapod three.
