I agree. It was also really a heartwarming thing seeing the Roses (Thorn, Rusty and Black Rose) viewing each other as sisters. Would have also been great if Sonic's friends met their counterparts. Amy would very likely invite her "sisters" for a solstice. And imagine what Sonic's and Shadow's counterparts from the three Shatterspaces would look like.
It was my favorite serie, but in the first season were too many badniks battles.
Shadow was nicer than all the others series and that was great. My favorite season was the third! It was so exciting!