Preface: I asked my crewmate Wv Khal Jesus for his thoughts, and between the two of us we discussed the MU at length. This is the result of that:
Sonic's main gameplan in neutral is getting you to commit to something he can spindash punish, as most of his damage comes from that. Since spindash itself has low priority, he'll mix up the timing using feints (cancelling the charge with shield), and mixup his approach with dash grab / dash shield / pivot f-tilts. Pressuring landings is also another one of his strenghts, as his speed allows him to chase them very easily. Nearing KO %s, he will fish for spindash to bair, back throws and f-tilts / f-smashes to push you offstage and seal the deal.
The matchup itself will usually boil down to mid-range posturing from both sides. Both can punish commitment from the other at this range, and also be close enough to try a mixup. Sonic is more likely to concede stage position in order to bait a response, so often, he will be pushed to the edge where he's no longer able to avoid commiting, and at this point, a spindash approach is likely to happen.
A big part of the matchup is knowing what Sonic can do during spindash. Here are the most common options:
- Jump + Spring out: Defensive option. The spring will cover his retreat, and he will be able to d-air and autocancel it to regain control quickly. Despite the autocancel, Sonic is vulnerable to u-air (easy to outprioritize his kick), or dash attack / dash grab on his landing. If he chooses to not d-air down, his only options in the air are aerials and airdodges. Chase his landing and punish him appropriately. Do not forget about the spring hitbox.
- Jump through: Defensive option. Sonic retains most of his options, but is now in the air in a disadvantaged position. There is no guaranteed punish here, but you should pressure his landing to force a response, or you can OoS b-air/u-air if you're quick enough and you don't expect him to Spring out immediately. Sonic will usually reset to neutral after this.
- Jump + Neutral B: Offensive option. If you remain in shield, it is very likely that the neutral B will shield poke. This will also punish slow OoS attempts. To punish this, you can either spotdodge or roll to avoid the attack and then punish him afterwards. Unfortunately, sometimes Sonic will not track Falcon and instead will end up away from you, making a punish harder. There's two types of neutral B, one faster than the other, which Sonic can control to mess up your timing.
- Preemptive jump / Spinshot: Offensive option. This is often used if you're trying to contest spindash directly (holding jab, for example) or trying to jump over the spindash mixups. Since Sonic retains most of his options, you must wait to see what he does next or try to contest him with an aerial.
It is generally a good thing to have Sonic spindash towards you, as holding jab will either beat it or clank with it 90% of the time, and shielding will force him to commit to something you can punish. U-air is a great tool to force Spring escapes, which in turn can be further pressured and punished. On Sonic's end, he will try to pressure landings rather than keep you juggled in the air.
The neutral situation feels roughly even to both of us. Both chars have the tools to pressure and punish each other, and it tends to come down to who has the better reads.
Advantage and disadvantage is a different story.
Onstage, Falcon has a better advantaged state. Sonic's floatiness makes it hard to land, and once the Spring escape-hatch is pulled, his options are severely restricted. Falcon also hits harder, both in damage and knockback, and Sonic is not particularly good at taking hits. When the situation is reversed, Falcon's fall speed makes it hard for Sonic to keep up juggles, and while f-air strings do carry him offstage, the damage they do is negligible.
Offstage, Sonic has the upper hand. F-air has enough knockback to outright gimp Falcon, and spring is also a very serious threat that will beat airdodges and gimp as well. It can sometimes be hard to tech the spring as it hits with a Sakurai angle, so the launch trajectory depends on %. When the situation is reversed, Sonic can afford to recover low without much threat, as he can vary the Spring timing to avoid getting spiked, and he is invincible from startup to about mid-height. If he has a jump, he can also spinshot (which also has slight invincibility) back to stage. Trying to go deep to edge guard him can easily result in getting gimped by the Spring in return.
As for stages, Sonic thrives in long stages that allow him to bait for as long as possible, and stages that let him reset to neutral easily. He struggles with inconsistent platform placements and heights, since it essentially cuts off the positions in which he can d-air back to stage with reasonable safety. Small stages also force him to go in often, which leaves him in a vulnerable position when the mixup fails.
With this in mind, these are the stages to avoid: Duck Hunt, Delfino, Skyloft, FD.
These are good counterpicks: Town and City, Battlefield.
And these it's hard to say who benefits more: Smashville, Castle Siege, Lylat, Halberd.
Here is a video that showcases plenty of this. @
-Fatality- , if you'd like to chime in, feel free