A moves
--------
Neutral A
Marth: 6%
Roy: 5%
Tilt Forward
Marth: 13%
Roy: 10%
Tilt Up
Marth: 12%
Roy: 8%
Tilt Down
Marth: 10%
Roy: 10%
Neutral Air
Marth: 13%
Roy: 11%
Forward Air
Marth: 13%
Roy: 8%
Back Air
Marth: 13%
Roy: 9%
Up Air
Marth: 13%
Roy: 6%
Down Air
Marth: 13%
Roy: 10%
Smash Forward
Marth: 20% uncharged, 27% charged
Roy: 20% uncharged, 27% charged
Smash Up
Marth: 18% uncharged, 24% charged
Roy: 16% uncharged, 22% charged
Smash Down
Marth: 16% uncharged, 21% charged
Roy: 21% uncharged, 28% charged
Who has stronger A moves?
Marth: 9
Roy: 1
B moves
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Neutral B
Marth: 7% uncharged, 28% charged
Roy: 6% uncharged, 50% charged
Forward B*
Marth: 4% 5% 10% 14%
Roy: 5% 6% 9% 11%
Up B
Marth: 13%
Roy: 13%
Down B
Marth: 7%
Roy: 1.5x attack countered
Who has stronger B moves?
Marth: 1
Roy: 2
Throws
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Forward Throw
Marth: 4%
Roy: 5%
Back Throw
Marth: 4%
Roy: 5%
Up Throw
Marth: 4%
Roy: 5%
Down Throw
Marth: 5%
Roy: 6%
Grab Attack
Marth: 3%
Roy: 3%
Who has stronger throws?
Marth: 0
Roy: 4
Who has stronger moves overall?
Marth: 10
Roy: 7
well there you have it folks, no fanboyism, just pure stats you can get for yourselves in training mode. i hope this helps you make a more informed decision about your character choice.
* - Each number corresponds to ONLY the attack of the Forward B for its position. For example, the third hit of Marth's Forward B does 10%. Also note, this is only using Forward B repeatedly, other variations were not tested, but feel free to check it for yourselves.
Marth also has more knockback, in addition to dealing more damage. Roy has the larger sweet spot, but if you test out their non-sweet spot attacks, Marth still beats Roy out, easily.
The moves Roy wins in are throws, down smash, Flare Blade and counter.
Roy wins in throws by a whopping one percent, and Roy's grabbing and throwing game is actually a disadvantage to him, since Roy can't chain throw and has a worse grab range.
Counter comes out slower, thus making it less useful than Marth's. Not lasting that long isn't an advantage for Roy, since you can time that, but you can't get over the fact that his counter comes out slower.
Flare Blade, which is useless except for maybe edgeguarding, is stronger (albeit slightly, since Flare Blade takes longer to charge up), but it can be blocked, while Marth's Shield Breaker will take off at least 1/3 of your shield uncharged.
Roy's down smash does more damage, but has less knockback, and comes out slower.
And then there's the basic stuff.
We can conclude that:
Marth is stronger than Roy.
Marth is heavier than Roy.
Marth is faster than Roy (in everything but falling speed)
Marth falls slower than Roy (making him harder to juggle)
Marth is heavier than Roy (making him harder to KO horizontally)
Marth can chain throw.
Marth has better grabs.
Marth's sweet spot maybe be better placed (weak attacks near him, strong attacks away to set up some interesting combos)
The attacks that Roy is stronger in are all less useful.
Marth has what is considered to be one of the best spikes in the game (aerial down+A), while Roy's suck.
Roy is harder to KO vertically.
GameFAQs'd/10 >.>