Originally Posted by Fat Yilx
...I strongly feel that some people are overthinking the impact of weather....
...making a mon weak to a type does not increase [that type's] usage....
I don't have too much to add as far as specific typings at this point, but I really want to emphasize these points that Yilx made. I feel a lot of people are trying to do way too much with typing alone and are way overthinking the impact that weather has in order to support typings or reject typings. Almost every single weather related argument has an equal and opposite counter argument.
Take Fire type for example. One person could argue that it is bad because it is water weak which Sun doesn't want to be going against ran. On the other hand, someone could argue that no type benifits more from sun, and since we want to be sure it sees more use on sun than elsewhere, it is a good typing. Such an opposite can be found almost every time someone tries to make an argument purely based on weather effects. We need to focus more on what potential a type brings to sun not simply how it interacts with weather. We have a bunch more stages to fix up and problems we have. A single type weakness (or lack of resistance) does not make a type useless to our purposes if it has the potential to help sun with a role that it needs.
As for the second point, well, I don't have much to add on here, so I'm just going to say this: While weakness to common types can prove disasterous on some Pokemon, this is an effect on itself, not the metagame. If they typing it is weak to is irrelivant to fufilling its job of increasing the prowess of sun, then it really doesn't matter.