Wow, I actually really like how this one turned out. Raichu's the only chu I like, although I may try a realistic Pikachu and Pichu later just to make them look better XP

Anyway, I imagine a Raichu as being built like a wallaby/hare/jerboa thing.. I've seen it drawn as a mouse several times, but come on, Mouse Pokémon is a (vague) description. After all, nobody thinks Blastoise is actually a Shellfish, do they? Its anatomy in official art doesn't suggest a mouselike critter at all.

The tail is also a conundrum, took me a while to figure out how to make it look like Raichu's tail and be believable, I've seen it rendered as a tuft of hair before but that seems like a cop-out to me. So here, the end of the tail is mostly made of cartilage, I figure the "bolt" part is mainly for display as it differs between male and female.