Originally Posted by Fat Temp V1
Back in the earlier days of BW1 I did run Hydro Pump on Mence, although this was before Moxie was released so most Mence sets were wallbreakers or DDs. It worked decently then because no one was expecting it, but it definitely didn't get me any more KOs than Fire Blast. I have used it a little in the BW2 metagame, but no more than 5 matches so its hard to conclusively say whether it works better than Fire Blast. On a rain team it wouldn't make a whole lot of sense to run Fire Blast, because apart from anything thats 4x weak to Fire, you won't be dealing all that much damage unless you really pump a lot of EVs into SATK. So in regards to that, it could be nice for slightly additional coverage, although with the list of things you mentioned a standard rain team should be able to beat them with relative ease. All up I don't really think Hydro Pump on Mence is an incredibly useful move, unless you really want to run a Mence on a rain team, which isn't really the best team type for even a ScarfMoxie Mence.
I'm going to have to agree with Temp here, rain isn't the best environment for salamence. His best counters are steels that love a rain dampened fire blast. I understand you run hyrdo pump instead but don't see that viable against a decent team. Ferrothorn then completely walls you, and can get spikes down or leech seed to get residual damage plus iron barbs. Personally I don't even bring out scarf moxie mence until all steels are gone or low enough to kill. I try and use him as strictly a late game sweeper, if I can help it I don't even use him to revenge kill.