How do you fuse in budokai tenkaichi 3

Its easy: Only certain characters can fuse here they are: Goku(GT)+Super Sayian 4 Vegeta(Goku(GT) has to be in super sayian 4 form to fuse) Vegeta(second form)+Goku(end) Trunks+Goten I dont know if these are all of em but i think so anyways this is how: Pick them both in a battle, i suggest for 1st time fusing Goten and Trunks anyways when u pick both of em go to skill list with either goten or trunks it doesnt matter,than go to the tab where the transforms are and it will show u how to fuse and how much blast stcoks(the blue things) it costs.IMPORTANT: you know it will be something like > r3 or < r3 or smthing like that but dont just press you need to hold it a bit. Hope i helped :)