I played Battlebond with my friends yesterday. I attacked with Gorm the Great and his partner Virtus the Veiled. The opponents had three untapped creatures. They blocked Gorm using two creatures and blocked Virtus with another creature. Can they block this way?
Yes, you can do that.
Gorm the Great needs to be blocked by at least 2 creatures:
Gorm the Great must be blocked if able, and Gorm must be blocked by two or more creatures if able.
If the opponent has any more creatures they can choose to block any creature with them (unless there are any other restrictions).
Gorm says the defending player has to block him if able. This has been satisfied.
Gorm says the defending player has to assign at least two blockers to Gorm if able. This has been satisfied.
Thus the block assignment is legal (assuming no other restrictions).
Compare to, for instance, Taunting Elf, which would almost guarantee that Virtus gets through.