Seeing them practicing the Jingiskhan dance together is already a sign that it will be a whacked out concert
I'd like to see both groups perform Suhada Pichi Pichi and maybe someone from Berryz do a cover of Tsuugaku Vector and someone from C-ute cover Sprinter or Natsu Remember You.
Tokaikko would definitely be in there (ChrNo sent me a clip from a radio show before and Miya was doing Maimi's lines , heck even Sayu was singing lines from the song
) Also, in the backstage vid of the Winter concert, Chisato was singing lines from Tsukiatteru no ni Kataomoi that gave Momo an 'eh?' face