What site are you thinking of?
A) Dose the site have sprites like this one does? Small detail but it really comes in handy.
B) My dad is very trigger happy with firewalls. Any site categorized as "Games" gets blocked. Serebii itself is blocked, but the forum isn't (b-t-dub, it would take just one update where the site gets categorized as "Games" for me to lose access. it happened before with Pokemon Online). Sometimes, like with Bulbapedia, the opposite is true. But eh, that's just me.
C) IK you said no noobs, but what happens when it NEEDS fresh blood? Serebii is popular enough that you don't need to reach out that much too find people, cause they find you. But if we go to some micro-forum off to the side of the internet, only that forum's small community can find us. And sometimes people are just reluctant to get started on a new site. Besides, the problem of noobs can be solved easily by not making Russ in charge of signups.