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Box starter and catch a Lillipup.
Its stats and access to Intimidate is extremely good for a Route 1 mon. Being a Normal type has its uses too.
STAB Return and the Dark-type Crunch is great for Ghosts, and you have a few other options like Work Up, Thunder Wave, Dig, Wild Charge, and in BW2, Iron Head and Superpower. It can learn Strength and Surf should you need to cough up a slot for field use.
It is also conventionally similar to a starter, being in the Medium-Slow EXP Yield and evolving at 16 and again at 32.