In addition to the elemental hero deck recommendations which I wholly support, I have this: I accidentally achieved this requirement at stage 24 using an Ojama lock deck, where I had summoned and lost my Ojama Knight and Ojama King, and using Ojama Country I resurrected them from the graveyard. Maybe it was a bug, but I got credit for the 4 fusions with just those two, having been recalled from the graveyard.
anoymous
Try a standard elemental hero deck with 3x elemental woodsman, 3x poly, 3x Elemental Hero Neos, 3x elemental hero heat and 3x elemental hero lady heat along with the elemnetal hero neos warrior fusion and the heat and lady heat fusion and go against easy opponent
anoymous
Try a standard elemental hero deck with 3x elemental woodsman, 3x poly, 3x Elemental Hero Neos, 3x elemental hero heat and 3x elemental hero lady heat along with the elemnetal hero neos warrior fusion and the heat and lady heat fusion and go against easy opponent
anoymous
Fusion gate.
anoymous
Fusion gate.
anoymous
Go against a lvl 10 LD at the gate, make a deck with Red-Eyes Fusions (there are like 4 now) and Buster Blader. Fusion summon 3, tribute summon 2 of the fusions with a 7-star monster, fusion again and GG
anoymous
Try a deck that recycles polymerization, or use master of fusion skill to add an extra copy.