If both players have all 5 of the cards listed on “Exodia the Forbidden One” in their hand at the same time, such as if both players start with all 5 of the cards in their opening hand, or if both players draw all 5 cards by the effect of “Card Destruction”, the game is declared a DRAW.
Netrep Rulings:
A win may be declared by holding all five Exodia pieces in between a chain.
A win may not be declared by holding all five Exodia pieces in between the resolution of an effect.
If both players hold all five pieces of Exodia at the same time, the duel is a Draw.
If the fifth Exodia piece is drawn and “Drop Off” is activated, the player who holds all five pieces of Exodia would still win.