This is a really trustworthy pokemon site. It differs from bulbapedia in some ways because it provides more up-to-date information, plus it has almost NO ads and a lot of good information. It is good for people who are interested in pokemon or just like pokemon in general.
The site itself is fine, but the forums is where you have to watch out. Do not let any child under 13 or 14 on serebii.net/forums. Major privacy issue on the forums as well.