>>22602966Expert on rain here.
Swampert is pretty okay in doubles, I guess. I mostly run TR in doubles so I'm not too well versed, but I've seen very very little of Mega Swampert. Most of the Rain teams I've ran into, every single one runs Ludicolo (who's really common, even on non-Rain, and shuts down Mega Swampert pretty hard) but most use different megas.
In singles, it's definitely better, and Kabutops' is about on the same level of viability (probably less) because it only hits marginally harder and is far less bulky, but doesn't take up the mega slot. But Kingdra is by and far the best Swift Swimmer due to its speed tier, secondary STAB, power, and ability to go mixed. And while Mega Swampert is much bulkier, Kingdra isn't the frailest thing there is.
Also Omastar is good.
