1. Select 200 random articles.
2. Get the top contributors for each of them.
3. Get the edit counts for those contributors.

I think he has the list/s of 200 articles, and does not want random ones.

Plus, he doesn't want the editcounts, he wants their top edited articles, with the editcount per article.

My personal opinion is that this HAS to be done via php (though I can't comment of server load).

Use php-mysql to determine the list of top contributors per given article, then loop for each contributor, and give his top edited articles... Shouldn't be hard, though you might want to clarify what you mean by "top". (Top 3? More than X edits? More than X% edits per day/week/month/beginning of time? More than X% edits of the top editor?).

-Manishearth