Pokemon Central runs ads (Google AdSense at that!), which is probably how they pay for everything.
Google is likely their biggest inbound source of traffic, so they're probably experiencing a marked revenue drop as well.
It's unfortunate that so many livelihoods are subject to the capricious whims of a single company. A company that is increasingly seeking to keep users on their engine without sending eyeballs or revenue to any third parties at all.
We're watching Google's "embrace-extend-extinguish" arc for the web. It's not over by a long shot, but they absolutely intend to finish the job.