If I have a Pokémon with an Everstone, it is possible to reach level 100 without that Pokémon evolving, starting with Generation 2. It is also possible to bypass the evolution manually in many generations.
If a Pokémon reaches level 100 without evolving to its final evolution, and it would evolve by leveling up (as opposed to by trading or other mechanics that do not require leveling up, but including methods such as evolving while leveling while holding a stone, or evolving with a certain friendship level), is it possible to evolve that Pokémon in any main series game?
Best Answer
Prior to Generation 8, it is not possible to evolve a Pokémon that is level 100 and requires leveling up to evolve.
In Generation 8 (the generation that launched with Pokémon Sword and Pokémon Shield), however, the mechanic of Rare Candy has changed slightly to enable evolving Pokémon at level 100:
This now allows the evolution of Pokémon who reach level 100 without evolving, if the user chooses.