How about a rating system for abilities & items? (And perhaps Pokemon)

[Unowninator]

This would show how good/useful they are. It could be x out of 5 (or 10). For example, things like Leftovers, Drizzle would be 5 out of 5, while Slow Start would be an obvious 0. I think it could really help some people in knowing what the best items/abilities are, especially if they're new to competitive battling. What do you think?

 

[DittoCrow]

Not sure if you're suggesting this for on-site or not, but if you are then that's not the place for this sort of thing. Pokemon are already ranked by tiers, Ubers has the strongest Pokemon, then OU, UU, etc. For ability and item ranking, you can make a thread in the Overused forum I guess. There's already one for abilities here.

Things like the best items and abilities are already on analyses for each Pokemon, so ranking items and abilities on-site would be unnecessary.

 

[capefeather]

It does seem interesting to have ACRE and GXE ratings for Pokemon, but that seems like more of a suggestion for PS! itself and I'm not sure how it would actually work out.

 

[verbatim]

Pokemon Showdown utilizes a -2 to 5 scale to rank abilities and determine their probability of occurring in Random Battle, a more detailed explanation of the ranking system, and every abilities corresponding rating can be found here. While items do not have such a corresponding system, they are much easier to rank than abilities due to the fact that you aren't forced into using them in order to gain something else, such as having to put up with Truant if you want to use Slaking, and thus only the top items 4-5 items ever see use, defeating the purpose of ranking them.

 

[Great Sage]

PS uses a rough rating system for abilities in its random battles algorithm for convenience. However, it is not possible to accurately capture an ability or item in one number, because these things do not exist in a vacuum and do vastly different things that are not comparable.