All the rules for Limited Tournaments (Section 7) apply, except as described below.
Eight boosters per team are recommended for Two-Headed Giant Sealed Deck tournaments and six boosters per team for Two-Headed Giant Booster Draft tournaments. For the recommended product mix for the current block, refer to Appendix D.
Cards not used in a team’s starting decks are considered a shared sideboard by the two players that both players can access.
Remember that while both players share the sideboard, matches are best of one game in Two-Headed Giant. Any tournament where the players may swap main deck and sideboard cards (e.g. where no decklists are used) make this rule important.