1. Beat 100 Man Brawl
2. Complete 50 Vs. Mode battles
3. Meet Falco in Subspace Emissary
This one could be difficult to unlock in 100 Man Brawl. Defeating 100 enemies in a row isn't ever easy. It may take a while but I think I will probably go for the 50 Vs. Mode battles on this one. You will have to clear 160 Vs. Mode battles in order to get R.O.B. anyway so you may as well get a few of these under your belt while you're at it. Sudden Death mode with 1 stock will get you quick battles to rack up the numbers. When fighting Falco, treat him just like Fox. He has some differences, but his basic moveset is very similar. Expect quick, hard hits and a laser to chase you when you run. Quick reflexes and perhaps some good items are probably your best bet with this guy. Of course if you don't want to fight him, you can always just get him to join your party in Subspace Emissary mode.
Every man dies, but few truly live. Live your life to its fullest, every day as if it were your last.