It depends on how far you are in the story. Zubat is also obtainable as soon as you can use Cut, and Crobat is fairly decent.
If you're asking because you want to beat Keta, maybe get a Simple (S)woobat and Calm Mind away?
Why not a Cofagrigus then? Mummy is a great ability, Will-O-Wisp makes physical hits much less painful, and Power Split neuters any offensive stats. Just make sure you heavily invest in HP (Gearen EV Lab) and Defense (Spewpas Goldenwood forest iirc.).
