If we're using 60:40 as a disadvantage, Snake wins this 60:40.
Sonic can be annoying to Snake. It's really hard for Snake to hit Sonic if Sonic so chooses to be like that, and his projectiles aren't going to do a whole lot in terms of camping with them. Sonic can capitalize on Snake's limited ground mobility a bit and attack him during his recovery.
This doesn't mean anything though compared to what Snake can do to Sonic.
1) First off, it's important to keep in mind the fact that this is Snake. His Ftilt does 21% damage. He can kill you as low as 100%. With proper DI he's not going to be dying until around 180%-200%.
2) He can use grenades whenever he wants, either shielding or not shielding. If he's shielding and you're not, you take 17% damage. If he's not shielding and you're not, you both take 17% damage. Due to the difference in weight though, Snake GLADLY takes the damage since Sonic is prone to die way earlier than Snake.
3) Snake outranges Sonic on the ground terribly, therefore forcing him to approach in the air or with Spin Dash/Homing Attack which Snake can easily stop both with good timing.
4) You are limited on approaches due to his Ftilt and Utilt covering most of your approaching options.
5) Basically, on stage they both have a ton of options against each other. It doesn't matter though. Snake is a juggernaut in Brawl. He deals ridiculous damage, kills at insanely low percents, and lives forever.
6) Sonic can't compete with this, no matter what he can abuse on the stage...Speed, beating Snake's recovery etc, staying out of tilting range etc. Fact is, you can play keep away all you want. Eventually you're going to need to get close to kill him, and you're just not going to be able to do it without taking an insane amount of damage.
Snake has a definite, clear advantage here.
First of all, thanks for actually coming and contributing XD
1) Ftilt is awesome, but I do think its overrated, at least in this matchup. It stales if overused quite a bit. If you are going to use it to kill, its easy to DI out of it, because you have more time to react since its a natural 2 hit combo. Its a good damager sure, but its not the end of the world. Again, Sonic's ASC does 18 damage, and followups are ridiculously easy as well so its usually 25+. Also, first hit of ftilt doesn't have the godly range of the second hit.
2) I think you underestimate Sonics grab game. Sonic Vs Snake is a particularly grab heavy match-up for Sonic. And its not as if grenades are particularly harmful to Sonic as opposed to other chars. You are however very correct about the damage:weight thing.
3) Not really terribly. Utilt is the scariest thing in this entire matchup IMO, so I'll give that to snake, because its godly. I believe it kills Sonic at 102% unstale with no DI on FD. Outranging on the ground isn't nearly as crucial as outranging in the air against Sonic IMO. Sonics tilts will clang with all of snake's tilts, and I'm pretty sure either equals or beats the range on the first hit of Snakes ftilt. And as Tenki mentioned, moving shield from a run, or SideB cancelling running shields deal well with the range issue.
4) Honestly, Sonic is never really limited in approach options against anyone except Olimar IMO, because almost all of his main approaches are cancellable. Sonics running shield grab deals pretty nicely with range issues as well.(shield hits hit, Sonic slides into grab range, grab). Especially against characters that have exploitable
ending lag on his moves, which Snake does have. I'm pretty Sure Sonic can cover at least a fourth or third of FD in the ending lag of Snake's ftilt.
5) Yea but can't you say that as well about Snake vs MK? And that matchup is usually deemed about neutral. And I actually think Sonic has some stuff over snake that MK doesnt have, Like, Sonic is heavier. And Sonic can arguably get past campy snakes better as well. Sonic can deal damage on any large character very well, so that coutneracts the weight issue. And because Snake has ending lag on his moves, and Sonic is quick, landing a KO on snake really isn't that difficult as it may seem once he's damages enough.
6) This is where I disagree the most. Sonic won't, or at least shouldn't be trying to stay outside of Snakes range too much. I think this is a battle best fought close quarters. Its very grab dependant for Sonic. Because of Sonic's cancellable approaches and running speed, getting in close without taking alot of damage should not be a problem.