The last three pay stubs is only required when you are in the US. While the beneficiary is abroad, the new company can file a H-1B Transfer for Consulate Processing without any pay stubs. Once approved, you can travel on the new H-1B Approval.

However, USCIS may issue a RFE asking for documents to establish that you had been maintaining your status while yo were in the US. Documents may include  pay stubs for the period you were in the US and Tax Return/W-2.