Makuhita are not a particularly powerful species of pokemon, nor is there all that much about them which captures the imagination of beginning trainers. When they are captured it is not often from favoritism, but almost always because Makuhita are among the most common fighting-type pokemon in Hoenn. And there are a great many trainers, two of Hoenn's gym leaders among them, who struggle to deal with fighting pokemon. Yet rarely are they imagined as a permanent member on a trainer's team, and if they are it is only to cover weaknesses; usually, they are seen as mercenaries to be used for a single match and then either released to the wild or deposited in the pokemon storage system.
Yet few Makuhita are ever released, for their trainers soon find in them a determination matching or even exceeding their own. They will spend day and night lifting weights until they pass out, often continuing after their trainer has already fallen asleep, trying to overcome their natural fatigue to gain more time for training. Makuhita are known for trying to push over trees as a show of strength, although they never succeed in anything more than making them sway a bit or knocking out smaller pokemon like Shroomish and Slakoth. Yet they still count every inch they sway the branch as a minor victory, and they dream of the day when they will be able to shove down trees, roots and all.
And then their trainers grow to identify with their Makuhita and see them as not only temporary minions, but as the truest of comrades. After all, pokemon trainers and Makuhita alike want to be the very best.