User:P.i./Brawl Online Guide

Super Smash Bros. Brawl can be played on a personal computer using Dolphin, or on a Wii or Wii U using Wiimmfi.

Dolphin netplay guide

First, make sure all players have the current netplay build.

Note: Both players must use the exact same Dolphin version (cross-platform is fine).

You must also have a Brawl ISO. You can back up your own copy legally. Do not ask where to download ISOs.

Many options in Dolphin must be specified exactly in order for netplay to work and to minimize desyncs.

Desync: Online desynchronization, when different players see different things happening in the game.

Right click Brawl in the Dolphin game list and go to Properties. Make sure the "Global Brawl Netplay Settings" and "Disable Challenger Approaches" codes are on. (Note: You won't have the C-stick codes by default. If you add any extra codes, they must be disabled for netplay.)
"Enable Cheats" must be turned on.
Most graphics settings won't cause desyncs. However it's important that your computer is able to consistently hit 60 fps. If necessary, make sure the internal resolution is "1x" and the various filtering options are off.