SpellJammer knows you fanboys are never going to accept the truth on either side. Vegeta WILL win even if he can't go super. (Which as stated countless times, SpellJammer refuses to count anything after Frieza saga..)
Vegeta's power level at the end of Frieza saga was around 80,000.
Sonic in his average form has to contend with Eggman's creations. Each of these robots or "androids" is significatly less stronger then the adroids Goku came across in his kid years during the Red Ribbon fiasco.. But also they're in alot more dangerous having machine gun arms, flame throwers, or being mammoth size.. But Goku didn't have to fight as many neither, and they still gave him trouble and his power level was around 37 (It was 10 when he first met Bulma..) so Sonic we'll say is a good 50-60..
When he obtains that Chaotix emralds and is able to transform, this transformation resembles super saiyan 3 in alot of ways, VERY powerful, but exhausts the body VERY quickly which is why he go's back to nromal so quickly much like Goku did in super saiyan 3.. We'll say when he transforms his power level jumps up to about 20,000. Which by Sonic standards is unstopable, but by DBZ standards is "okay".
Where do I get 20,000? Well Oozaru form of a saiyan and super saiyan 1 pretty much pump them up by the same volume which is 10xnormal power level. Ten times 50 is 500. Super saiyan 2 only increases it maybe 1/2 more so we say 750, then super saiyan 3 takes the volume up to 11 and because SpellJammer is giving Sonic the bennefit of the doubt here, he's going to say 20,000. Which is a longshot. But even with that much bias Sonic still does not have the energy levels to contend with Vegeta. His speed may be greater much like Burter from Ginyu Force. But without the proper energy needed to countie that velocity at an alarming rate, and the transformation ending fairly quickly, it's not long before Sonic is sent to "the next dimension"..
Also Vegeta can sense energy, Sonic can't. Vegeta could so easily pull a sneak attack and rip Sonic limb from limb before he can even react..