It would appear that newly-signed WWE talent Cain Velasquez is not officially associated with a brand.
He is scheduled to remain with Rey Mysterio through this month to build to his WWE Championship match against Brock Lesnar at Crown Jewel, per Dave Meltzer. However, this presents an obvious issue as Mysterio is a Raw Superstar and Lesnar is on SmackDown. It’s possible WWE won’t address his brand status until after Crown Jewel on Oct. 31.
We should note WWE has announced a Mysterio/Velasquez tag team for their Nov. 30 show in Mexico.