>>37196662They literally named "Isn't it strange?" because it has no specific origin. Masuda said it's a mix of different things and that's why it's the most pokemon-ish looking Pokemon in his opinion.
and just because Sugimori said it's a frog doesn't mean it didn't take inspirations from different animals.
Squirtle is named "tiny turtle' and Charmander is "lizard" in Japanese, if Bulbasaur was pure frog they would named it "frog' but they went for "isn't it strange?" because it's a mix of different animals.
