yes
Not sure but maybe.
I think but do the festival mode on single
just click on them but if you are playing it on the nentendo then no cant
you have to beat them (final boss) then bowser Jr. and metal sonic (after beating eggman & bowser and after you complete all their challenges ) then beat eggman and bowser again the they will "follow" you.
The answer is Bowser, Eggman, Bowser Jr, Metal Sonic.
from the left, bowser eggman, bowser jr., metal sonic.
Bowser, Bowser Jr., Metal Sonic and Dr. Eggman.
Bowser Jr., Metal Sonic, Bowser and Dr. Eggman.
You beat all the challenges bowser jr and metal sonic put up and when you finish the missions go beat bowser and eggman again and they will join you.
Broswer all the way except for the last one it is eggman
If you mean in Adventure Tour on DS, they are in Blitzland. You need to get through a puzzle of pipes with Mario to reach them.
First you hit the Bowser Jr. symbol, then metal Sonic, then Eggman and finally the pumpkin.