Get all the Exodia pieces, into the graveyard, then Back-Up Soldier/Dark Factory them out, and into your hand.
Use
Obliterate!!! to get most of them into the Graveyard, also you can summon
The Legendary Exodia Incarnate to get a High Attack Monster out just by send ing a piece to the Graveyard, but only when you have a lot of pieces in said Graveyard. All of the Link monsters in the extra deck are to help with Grinder Golem, which is to help with getting the pieces to the grave.