Originally Posted by Fat PK Gaming
There are times where you need Hydro Pumps absurd power to OHKO a threat that would otherwise would be extremely difficult for your team to deal with. Surf is absolutely strong in the rain, but it doesn't have Hydro Pumps killing power. For example:
Surf vs Tornadus-T: 65.6% - 77.6%
Hydro Pump vs Tornadus-T: 82.6% - 97.7%
Surf doesn't come close to OHKOing Tornadus-T, even with SR most of the time. Hydro Pump on the other hand always OHKOes Tornadus-T after SR.
Hydro Pump's increased power is also useful against standard DD Dragonite (who takes a whopping 35.3% - 41.8% from Hydro Pump) and is outsped after a DD if it's Adamant natured. It doesn't sound impressive on paper, but when you take into account SR, and prior damage (and the fact thats its DD Dragonite!) It's great that you can deal 70% on average against DDnite if you land those 2 Hydro Pumps.
Another case of Hydro Pump being useful is against Rotom-W (it eats 39.6% - 46.5% from Hydro Pump). That said, Hydro Pump is unreliable due to its shaky accuracy, and there are times where you need that guaranteed surf in order to win, and that's why I opt to use both of those moves on the same set.
Politoed's other moves aren't seeing much use anyway, so its not that big of a deal if you miss out on HP grass or w/e.
Allright, I'll get your point :)
Thank you very much for your explanation!
Maybe I'll try this one one time, because I'm running a Rain-Team atm...