He's an alright attacker, but there are always better options.
If you don't have any other decent Earthquake users (you mention you don't have a Rhydon one, but Golem is decent enough), it's probably worth powering him to level 30, but I'd only potentially do it if Raikou is a current raid boss for you. Even then, we're most of the way through the month now, so even that need might not be there.
Also, I'd probably fast TM him to Counter as it's generally more useful, having much better type coverage than Tackle, and is useful against some top defenders like Blissey and Snorlax.
