I don't think Drampa looks like the acid-spitting type. It doesn't get a single Poison-type attack (besides Toxic). The Treeko line is in the same situation. But I agree with everything else, and I think Octillery, Cradily line, and maybe Seismitoad should get Acid Melt too.
EDIT: Otilery because ink, so I don't think Blastoise and Clawitzer fit.