>>40420535>nowThey've always done this for the starters. They've always designed each starter around a single personality trait.
For example, for Gen 5, Snivy was "cool", Tepig was "funny", and Oshawott was "serious".
http://lavacutcontent.com/ken-sugimori-nintendo-dream-3/>Sugimori: “We always divide the roles for the three starter Pokémon, by which I mean we assign each of them a distinct personality. For example, we make a cool one, a serious one, and a funny one. When we agreed on the concepts for Tepig and Snivy, we decided Tepig would be the funny one, and Snivy would be the cool one. So we knew Oshawott would have to be the serious one, which is how he ended up with the facial expression you see in his final design.” 