To cut down on sticky spam, we have condensed all the guides into this thread. Check here to see if the answer to your question is posted. If not, create a new thread or post an in existing help thread. Guides Run A Server on Windows Originally by Steve Client Installation Guide for Mac by Gilad Client Installation Guide for Mac using Crossover by Gilad Client Installation Guide for Linux Originally by masterhigh Building your team, challenging people, or changing tiers by Asagi Teambuilding for PO V2 by Emperor PPP Importing a team on Android Troubleshooting Pokemon Online stops working when opening Team Builder by Latios It asks me to run the simulator as an administrator? A: Don't install the simulator into Program Files. I can't save my team? A: Don't install the simulator into Program Files. There are no servers in the Server List? A: Try disabling your firewall. If that doesn't work, then that usually means Server Registry is down. Disconnected from the registry: Connection timed out. What do I do? A: Check firewall and/or antivirus. I can connect but not chat, battle, or see other users' messages? A: Post in this help thread and someone will try to help you out. Open Source Development If you want to help with the development of Pokemon online (C++ Programming), first thing to do is talk to the lead developer - coyotte508. You can also start by reading this thread: Run from source on Windows. The project is hosted at GitHub.
There is also PO available for older Macs now. http://valssi.fixme.fi/~lamperi/pokemononline/Pokemon-Online-TigerLeo.dmg contains 1.0.11 which works at least on Intel Tiger, Leopard and Snow Leopard. It has PPC binaries too but no one has tested it on PPC.
If anybody wants to port the Mac, Linux, or Android guides to the wiki then that'd be great. http://wiki.pokemon-online.eu/view/PO:Installation