Here's an idea I know myself, and several others who use this game think would be good.
I know Pokemon Showdown is dedicated towards competitive battling. And that's great. But most of my friends and myself greatly prefer random. With that said, I have some suggestions.
I think you should flesh out Pokemon Showdown Random Battles. Keeping what you have now, but adding options such as, unevolved Random Battles, and, Gen 1 Random Battles, Gen 2 Random Battles, Gen 3 Random battles, etc.
This narrows down the feel and adds more compelling battles (especially unevolved, giving more use to pokemon that arent normally used or offered) and I think a lot of people would like it.
I know it's probably a lot of work but I'm sure people would be interested.