Isn't having a fire move on a rain team kinda silly anyway? I don't do damage calcs for my teams (lazy), but it might be worth doing some for overheat and flamethrower to see whether it does enough damage to important opponents to justify using it. If it is underwhelming, hp ice seems like the next best choice (not many other options anyway unless you want to use physical moves for some reason). Actually, you could also try using protect so you can use surf without having to switch out (you have absorb bulb ludicolo though so it might not be necessary unless there is some opponent out that you don't want to switch ludicolo into for some reason).
Also, are you using Lightningrod? You said that Manectric 'takes the electric attacks aimed at Politoed" so I assume you are. If not, you should be!
Politoed and Manectric seems like a cool lead duo for a rain team. Good job.
@hockeyguy605: Good to see you had some success. I know how awesome lead scarf Darmanitan is. I do think that Cloyster is a strange choice for a backup though. As you said yourself, you can't really switch it in on direct attacks as they break the sash. This means that if you need to switch out Darmanitan and you predict an attack, Latios is your only choice, which may not be a good thing if it can't beat the opponent.