As a Pokémon expert, I can tell you that Ash's Bulbasaur and Squirtle do evolve during the series, but not without some unique circumstances and decisions made by Ash himself.

In the original Pokémon series, Ash's Bulbasaur evolves into an Ivysaur in episode 12, titled "Here Comes the Squirtle Squad," and later into a Venusaur during the橘子群岛 (Orange Islands) arc, specifically in episode 105, "The Battle of the Badge." This evolution is significant as it's one of the first times we see an Ash's Pokémon evolve on screen.

As for Squirtle, it evolves into a Wartortle in episode 18, "The Battle of the Badge," and then into a Blastoise in episode 58, "The Battle at the Beach!" However, there's a twist. Ash's Blastoise is loaned to Professor Oak for a while and is not seen for a long period in the series. It's worth noting that Ash's decision to evolve his Pokémon is often influenced by the battles and the needs of his team at the time.

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Squirtle is the only member of Ash's original team of six (Pikachu, Butterfree, Pidgeot, Bulbasaur, Charizard, and itself) that has neither evolved nor ever explicitly refused to evolve. Squirtle is the first of Ash's Pok��mon to have been placed in a Pok�� Ball off-screen, the other being Lapras.read more >>