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Kanto: Ash's Bulbasaur evolving into Ivysaur (granted, this one's admittedly in hindisght of the team that the Pokemon Trainer uses in Smash) Johto: Ash's Cyndaquil evolving into Quilava Hoenn: May's Skitty evolving into Delcatty, Brock's Marshtomp evolving into Swampert Sinnoh: Ash's Quilava...

Corphish probably didn't evolve because its evolved form is part Dark, and I feel like back then the writers were kinda opposed to giving the main hero a Pokemon of the "evil" type. Heck, even when Ash actually did get Dark-type Pokemon notice how the Dark aspect of them is always heavily...

I think wether a Pokemon evolves or not depends on several different factors: Character Development. Some Pokemon evolve either as a culmination of a character arc (Pignite, Incineroar) or as a leadup to the climax of it (Charizard's disobedience, Bayleef's fondness of Ash, Infernape's issues...