In the most recent event in Duels Links, they have us using Grandpa's signature cards, the five pieces of Exodia. While you are not required to win using Exodia, it is fun to do so. You still are required to have at least 20 cards in your deck, plus the 5 pieces of Exodia. While it is cool to have Exodia in your deck, it is not really practical. So, let's find out the best cards to use to get Exodia in your hand.
Fairy Draw has you thinning out your deck by using The Agent of Creation Venus's effect to special summon Mystic Shine Balls and then use White Elephant's Gift spell card to tribute a normal monster to draw two more cards. You can also use Cards from the Sky to remove a light fairy monster from your hand to draw two cards.
Heart of the Underdog:
With this combo, we use the Heart of the Underdog effect to keep drawing cards. If you draw a normal monster card, if you reveal your card, you can draw another card. You can also summon a normal monster, then use White Elephant's Gift to tribute a normal monster and draw two cards. Keep drawing until you get Exodia.
Use the effect of Magical Merchant to dump your monster cards into the graveyard until you draw a spell or trap card. Then use cards that add cards from your graveyard to your hand such as Backup Soldier, Painful Return etc to add the pieces of Exodia to your hand.
Just add any cards that let you draw to these decks and you will be calling out Exodia in no time flat.
Emissary of the Afterlife
Blue Dragon Summoner
Legion the Fiend Jester
Shard of Greed
Cup of AceWonder Wand
Jar of Greed
Having five extra cards in your deck can slow down your deck, especially weak ATK cards like Exodia. But adding cards that let you search for or draw more cards can help speed up the process of getting Exodia in your deck. Most players are opting to use the "Thin Out Your Deck System" so you have higher chances of drawing Exodia, or just adding a lot of cards that let you draw. So, it really is up to you how you build your own deck.