Now the whole battle won't be on the ground. There is the air too. Ike handles himself in the air fairly well since nair makes a good aerial shield. Fair outranges anything Sonic has in the air. Bair is fast in general. And dair and uair are lingering hitboxes.
The reason I didn't quite mention Ike's airgame was because it's somewhat exploitable.
Like, you have Ike's rising time, then the aerial startup lag (it's really noticeable D: ), ending lag, landing lag and such. Like KID mentioned,
Sonic can run in and F-air Ike from out of retreating F-air range (let's say 6 frame startup for jump startup+F-air startup time - not counting the time it takes for Sonic to close distance from the ground before he jumps). So if we don't wait until after your aerial comes out to punish you, we can still close distance/ruin spacing while you're moving upwards - even get under or
behind you, depending on which aerial you use.
When you jump, it gives us openings to use spindash/spincharge, because we can either use its lessened height to get under your aerials or hit you from below while setting up for a combo/followup hit.
Ike seems to have trouble defending from around shorthop height, in front of/below him. His N-air and F-air all sort of begin from the top and have to make their way downwards. More often than not, I'll have to deal with an airdodge.
But you know what though, here's what you can do that worked for metroid (the Ike player) for a few games (he 2stocked me pretty consistently before I caught on): If the Sonic player tends to run in and SH F-air when you jump,
don't airdodge (TRAP!), double jump and do a falling/long-reaching aerial.
If I'm wrong, you can go ahead and correct me, but that's just what I've seen lol.
edit:
I'm not exaggerating Sonic's speed lol.
http://www.youtube.com/watch?v=bljZ8SL8EXk