I was on serebii just now looking at the confirmed pokemon and I just thought: What would happen if somebody DDoS'd serebii.net? (Mind you, I'm not planning anything, this thread is purely for speculation.)
So, to start, you'd have to break it down to
1. If the site has protection (cloudflare, etc.)
2. How long the site would be down for (most likely no more than a few hours)
3. What would be the result of the downtime?

I'm assuming they have no cloudflare protection since I doubt the site makes enough revenue to pay for that, making protection a moneypit. For the sake of speculation, let's assume there's no DDoS protection and that a DDoS attack would be successful.
For the second part, let's say joe realizes the site's down within 5 minutes of it being down (whether it be through him checking the site or somebody tweeting at him). The amount of time for which the site would be down is variable and there's no way to know for sure how long the site would take to get back up, so let's make the range anywhere from 30 minutes to 5 hours.
This is the tricky part: what is the effect of this? How do serebii users react? How does joe react?