Mixed attacking Tyranitar is a pretty safe switch for Politoed since Tyranitar cannot threaten it tooooo much while Politoed threatens to burn with Scald, or just Toxic it and outlast it. You could try running Thunderbolt, but you will lose the coverage against other key threats, and politoed can always Protect to scout, and then switch out safely if you reveal Thunderbolt.
In a Hippowdon vs Politoed weather matchup, its pretty even in my view. Hippowdon can Slack Off Scald damage (provided Sand is up) and can use Earthquake to gradually wear down Politoed. No matter how you look at it tho, it would be a war of attrition with you attempting to outlast it, rather than blasting it down. In your senario however, its kinda tricky to assert what your opponent will do when we don't know teams, the levels of health both pokemon are on, moves, what weather is actually up etc etc. Any half decent opponent will look at your team at Turn 1 and figure out what he or she needs to do in order to win. It might be weakening your CM Reuniclus for SD Toxicroak to get a clean OHKO with Sucker Punch, letting him sweep, it might be KOing Specially Defensive Jirachi in order for Tornados to rip the game open with a few Hurricanes. It might be, that your opponent realises that you are weak to X, realises that your Hippowdon is set up fodder for X, and therefore coolly sacs there Politoed to your Hippowdon, knowing that they win the weather war, but then send in X and sweep. Basically, your scenario is always going to come up with different answers depending on what you and your opponent both have and therefore there is no "right answer" that you seem to be looking for.
To answer the new question tho, I personally wouldn't give Tyranitar Thunder JUST to deal with toed. If it a really, really big issue then o.k, maybe I would consider it, but personally, I would add an anti rain sweeper like Virizion (which sets up on Politoed) rather than running a dedicated moveslot just for Politoed.
