Daxter is basically a weasel. Technically they call him an "Ottsel," but close enough. He only has one game where he is the main character, the obviously named Daxter, but he is also playable in short sections in Jak II, Jak 3, and Jak & Daxter: The Lost Frontier. He's also a playable racer in Jak X: Combat Racing, but in story mode, you only play as Jak (with Daxter riding along and acting like you're playing as both of them, but you're not really, which is how it works for most of the series).
Sonic has Nack the Weasel, playable in Sonic Drift 2 and Sonic the Fighters. However, that's just his localized name, and his Japanese name is Fang the Sniper. That doesn't say he's not a weasel, since Sniper isn't a species, but apparently some deep lore stuff says he's actually a jerboa. But nobody knows that and everyone just thinks he's a weasel, including the comics he's appeared in.