Hiroshi Sotomura is the main style-maker, although there are various other people that make styles. You could check announcements for the announcement of each new one, I believe it would show the creator.
Hey, I thought I'd let you know more about styles since you seem interested but not too informed on the logistics.
Not every mod can make a style. In fact, less than 10 non-admins have been involved in style-making at PC as far as I know. The Stunfisk style, as a collaboration between Forever and Kip, took them quite a bit of time, and that was something that they were both dedicated to because they wanted to make it. That's generally how styles go - someone who has the ability to make a style works on it because they want to make a particular style, not because someone else asked them to. Because it's a ton of work - Every single graphic has to be made, everything has to fit in the right place, etc.
That's why, at least as far as I see it, trying to force style-makers to make themes based off of "popular" Pokemon on a certain time schedule isn't realistic in the slightest, lol. Most mods (myself included) probably don't even know how to make a style, so it would be up to the few mods/admins that do, and it would turn style-making into something really unfun for them, a job instead of something they do on their own time for fun.
Although you're welcome to suggest styles and maybe a style-maker will find it fun, that's about the best you'll get I think. xD