I'm sorry I forgot, but if the normal play button doesn't work, try this:
it can get around some firewalls.
WARNING: the port 80 version gets around firewalls, but it's also attacked by other firewalls, so only use it if the normal version doesn't work.
Pokemon Showdown | Replay player | No, I am not impressed that you know that my name is Guangcong Luo. The PS website says "Copyright Guangcong Luo" at the bottom, ffs.