Afraid not. The Move Maniac only allows you to relearn moves learned by leveling up for that particular Pokémon only, and not preevolutions.
If you want a Hydro Pump Raguraaji with some other Raguraaji moves, you'll have to delay Mudkip's evolution until it learns Hydro Pump, then let it evolve. After that, use the Move Maniac to relearn moves Raguraaji would've missed (e.g. Muddy Stream).