What about those Pokemon that don't evolve? They can't use the push of evolution to improve their talent. Another example of the disadvantages of the Talent System, it makes single stage Pokemon very non desirable, even if they were already unpopular IRL.
it might be interesting for the MC to restrict Rhyhorn's leveling. This is because Rhyhorn learns earthquakes and other attacks earlier than in his evolved Rhydon form.
It's the same for Machop, who learns certain techniques earlier. Allowing the MC to acquire more resources and the pokemon to increase the level of certain attacks, will surely allow the MC to improve the overall potential.
Rhyhorn and Machop can augment their talents through rarer and more complicated methods of evolution. Because, more difficulty = more power
Examples: margikarp for gyarados, feebas for milotic, and pokemon that evolve at very high levels