For me:
Not enough data: I don't have enough data to categorically say one way or the other how the matchup plays out.
Good: Matchups that Samus has an advantage in.
Even: Matchups that are at worst 50/50 - Samus has an equal chance as her opponent to win.
Bad: Matchups that Samus will lose most of the time, unless you majorly outplay your opponent. These are not impossible but are a big struggle. May rely on the opponent being unfamiliar with the matchup.
Ugly: Matchups that I believe Samus will lose 100% of the time given 2 players of equal skill.
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Not enough data:
Peach, Bowser Jr, Meta Knight, Ryu, Mii Gunner, Mii Swordfighter
Good:
Bowser, Charizard
Even:
Luigi, Yoshi, Donkey Kong, Little Mac, Ganondorf, Palutena, Marth, Ike, Robin, King Dedede, Greninja, Shulk, Lucina, Mega Man
Bad:
Diddy Kong, Link, Zelda, Sheik, Toon Link, Zero Suit Samus, Pit, Kirby, Pikachu, Lucario, Jigglypuff, Ness, Captain Falcon, Wii Fit Trainer, Dr. Mario, Dark Pit, Lucas, Roy, Mii Brawler
Ugly:
Mario, Rosalina & Luma, Wario, Mr Game & Watch, Duck Hunt Duo, Fox, Falco, R.O.B., Villager, Olimar, Pac-Man, Sonic, Mewtwo
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