The usual Cloudian farm deck can work here. However, since Sora has several cards that can add a card from his deck, he can end up decking out before the usual play of a farm deck. Having multiple copies of Zeradias and Sanctuary in the Sky can help give you thin the deck a little.
The main play is simply summoning any Cloudian and having Sanctuary in the Sky or Spirit Barrier on the field. There isn't much that Sora can do to out this board. Keep summoning until you have 3 monsters so that you can tribute summon into Winged Dragon of Ra and equip with Ceal to attack directly.
Use the Divine Punishment to stop/prevent Toy Vendor and/or Frightfur Patchwork to prevent Sora from drawing cards.
Acid Cloud with 2 Cloud counters can also destroy the Toy Vendor.
Having Fairy's Smile skill helps get enough LP so that you can get Ra's attack to over 10k, even after equipping Ceal. Since Sora is in Arc-V, the only character with Fairy's Smile is Zuzu. You can still do this without using the skill and get around 5k/6k points because there's a bonus reward event going on and you can use a bonus reward gem before starting the duel if you need it.