Sonic would win with how many forms he has to choose from, especially one in particular that pretty much trumps all As much as I amor my boy Shadow, the man canonically has fewer forms then Sonic does and none of them can parte superior, arriba Sonic's best
They both have super, are around evenly matched, maybe Shadow is stronger without inhibitors, however, Sonic has a hyper form (Canonically, Shadow doesn't) which is a step above super, Sonic can pretty much win with that But then we have forms like Excalibur Sonic and Darkspine Sonic (which may be as powerful as Super) that just add on Then we have werehog for no reason at all.
Yea... Shadow ain't winning this one. Sonic doesn't even need the other forms if he can spam Hyper as many times as he wants to, the other forms are just there for mostrar at that point.