I've played the Pokemon Leaf Green rom with rare candies cheats, and my lvl 100 Pokemon always get critical hits. Also, my friend traded me a lvl 100 flygon for Pokemon Black 2, which also gets alot of critical hits. Does the rate of getting one increase?
Short answer, no, at least not to the public's knowledge.
A Pokemon's level only increases the boost you get from critical hits.
>For example, a level 5 Pokémon will inflict 1.5× the damage on a critical hit, while a level 20 Pokémon will inflict 1.8× and a level 95 Pokémon will inflict 1.95×.