It looks like Azurilland hasn't been fully updated with sun and moon yet. Something like a team building tool is something that would have to be changed a lot with new games coming out, so it's probably down because they're updating it. (I don't know why they would have to take it down. Maybe it would save money by not having a flash plugin or whatever it is on their website, since not many people would use it since it's outdated.)
Also, lots of people use Smogon's showdown now, along with their competitive pokedex to effectively do the same thing as this Azurilland team builder, so maybe they don't plan on bringing it back.