Stage choice Tips for Falco vs Mario
Mario
For Mario, Battlefield and Pokemon Stadium 2 are really good choices, as they allow Mario up-air strings to be used more efficiently. Mario's combos also flow a lot better with platforms in mind, so use stages like Battlefield, Pokemon Stadium 2, and Smashville to your advantage. For a counter-pick, Unova or Kalos Pokemon League, are good stages with walls that Mario can take advantage of and platforms that can extend his combos. So play safe and only go in when there is an opening.
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Falco