When I made this list, for each character, I asked myself these questions?

1. Are they popular?
2. Are they in good quality games?
3. Have they been on a Nintendo console?
4. Do they have a realistic chance of getting in?
5. Would they fit into Smash Bros. well?

I feel everybody on my list has these qualities. It's difficult for me to satisfy everybody by limiting it to only 50 characters, but as Aesop once said: "If you try to please everybody, you'll end up pleasing nobody."