Spike Seadra and Thunder Dragon.
Spike Seadra and Thunder Dragon are probably the best cards that you can use to fuse a Twin-headed Thunder Dragon. Thunder Dragon is good because it will fuse with either a Thunder(like Tripwire Beast) or a Dragon(like Baby Dragon) monster and make a Twin-headed Thunder Dragon either way. Just don't fuse Dragon Zombie with TD.
Spike Seadra is good because you can fuse it with a Spellcaster(like Rogue Doll) and then fuse Kaminari Attack(the result of SS+Spellcaster) with a Dragon to fuse a Twin-headed Thunder Dragon. This is a great fusion if you have no Thunder monsters in your hand.
We have more cheats and tips for this game here, Yu-Gi-Oh! Forbidden Memories cheats
Comments for this hint