I think some people are completely missing the point of this thread.
We are not here to discuss HOW to defeat certain pokemon, we are here to discuss IF we should beat certain Pokemon. A small amount of polljumping may be required, but do not do any major discussion of what to give this CAP to cover its to-counter list or how to give it drawbacks that make it lose to its counters list
For example, I disagree with Deck on a lot of his list. Most of that looks good in theory, but as Ginga pointed out, i am more than a little wary of making cap5 a catch-all rain counter that also sucks against sun, because we definitely don't want to swing too hard in the other direction and break sun. I think giving sun the tools it lacks to be successful is good, but that slapping them all on the same Pokemon is bad—cap5 should be taking a supportin role with its teammates, not stealing the show. I think that situations like Rhys outlined are good, because they show give-and-take between the teams, not sun hanging rain in the town square by its small intestine. As such, i think it is perfectly fine to be countered by certain rain pokemon, like Rachi, ferro, scizor, and loltoxicroak (who if he's threatening your sun team you should rethink your life).
EDIT: while I'm here I should give a mention to threadhoging. Please don't. Threadhogging is defined as making a flurry of posts with a few other users in response to each other instead of the community at large. I know it's acceptable in other places, but we try to shy away from it here. Just to give you an example there have been two instances already on this page—not to call out these users: between alexwolf and mariowithlasers at top, and between alexwolf, forestflamerunner, and toomuchsugar right above me. It just makes it hard to hear other people amidst the noise. Thanks.