Here's some I would love to see
Flying Type Ponyta/Rapidash
Bug Type Trapinch
Bug/Dragon Type Vibrava/Flygon
Steel/Dragon Typer Deino/Zweilous/Hydreigon(Based on their original design plans)
Fire/Bug Type Durant
Water Type Hippopotas/Hippowdon
Water/Dragon Type Gible/Gabite/Garchomp...
They already can have those moves. While pretty rare now since Dream World went down, Lunatone and Solrock caught in the DW would have Moonlight and Morning Sun sometimes.
They should just add them to their level-up movepool now though.