Can you fuse in dbz budokai tenkaichi 3

Yes there is you make sure your chi is "5" than go to the menu go to the 1st one down from continue click it use the nun chuck and go right or left till you reach your evolutions and it will tell you what buttons to use to fuse
P.S. make sure you have the people that have to fuse in your group ( Example: Vegeta and Goku Gogeta) hope this helps