Not too familiar with Scraps, so I won't be helping you with the main deck to avoid getting flamed. As for your Extra Deck...
3 Scrap Dragon (YOUR KING.)
1 Ally of Justice Catastor
1 Arcanite Magician (Random moments with Goblin + Monk.)
1 Black Rose Dragon
1 Brionac, Dragon of the Ice Barrier
1 Colossal Fighter
1 Stardust Dragon
1 Trishula, Dragon of the Ice Barrier
1 Steelswarm Roach
1 Gem-Knight Pearl
That leaves you 3 more slots for you to fill in. I might miss some cards out, so feel free to fill the last 3 slots with them!