>>45229707Sugimori specifically listed Oshawott line as Serious, Snivy as Cool and Tepig as funny, for what it's worth.
Frankly when you look back, it's important to pay attention to the whole line in general. Hoenn we can be fairly sure that Blaziken is cool, Sceptile is serious and Swampert is funny because even though Swampert is not comedic both Mudkip and Marshtomp both have those goofy faces. DP though I have trouble deciding if Torterra or Empoleon is the funny one since depending on who you ask a chubby regal Penguin is likely funnier than turtle with a goofy face.
It's funny you brought Gen 8 up, because Ohmoro specifically said they broke up from the usual Starter creation proccess for that and instead tried to make "one for outgoing people, one for timid people and one for more balanced socially people", namely Scorbunny Sobble and Grooky.