What you need:

• Super Smash Flash 2 ver1.2.1
  • Downloads: All OS's

Controller Options:

• Keyboard
  
  • Setup in game
• Xpadder
  • Guide/Download
• Joy2Key
  • Download

Setup:

Download and Extract SSF2 anywhere on your comp. 

Depending on how you want to play, make sure you have an input device installed/ready to play before you launch SSF2.exe.

Go to http://mgn.mcleodgaming.com/account/register To Register for an online account: 

When you're ready, launch SSF2.exe:

For Controller setup, refer to this: Controller Setup

To Play Online:

Go to Online and enter the account info you created earlier (and verified):

To Join: 

Find your opponent's name under creator and click on the room name. Press Join Room! and Enter the given password (from your opponent) and you should be good:

To Host:

Press Create Room and input the name of the room/password of your choice (Keep it clean please):

Select Your Character:

Select whatever game mode you desire then hit ok: 

At this point, wait for your opponent to join. Once they join, you may select a stage and you guys will play on whatever stage the host picks:

And you're done!

Quick Reminders:

If you get stuck on a blank screen, please wait screen, hit Ctrl + W to end the game and start it over again. 

It is highly recommended that you restart the game after every set.

Manually adjusting the window size will most likely cause the game to lag. Hitting ctrl+ f will toggle full screen mode where it is less likely to lag.