Choice Scarf revenge killing set is always nice, and I see the point on Focus Blast, although I still prefer it, there is just one niche about this one. a Pokemon with a 90 base Sp Atk stat, even when maxed, has trouble running something like HP Grass.
The only thing you're really getting ahead of is Swampert, Gastrodon and friends.
While I think something like Focus Blast would still be better, I would consider using Psychic, or Focus Blast, while Focus Blast has crappy accuracy, it's still probably the best choice on Politoed. Although, I think you should take the Bulky approach on Politoed. Being a weather lead, you know Poli needs to stay alive ( Keep the rain going in weather wars ) and with no HP invest, Physical moves are going to OHKO without a problem or anything stopping them. Scarf toed with Modest still isn't that fast.
I would at least test out a 252 Hp, 252 Sp Def, 4 Def, Toed, with Scald, Ice Beam, Focus Blast, and Attract. Makes a great disrupter, Scald burns and screws physical enemies, Focus Blast can afford to miss with Attract support ( Yes, I said attract. Everyone says it's lame because of the practical 50/50 chance to actually be able to use it, but just try it ). Now that that little rant is over.. Yeah, just try that out a few times.