IMM 5406 (Additional Family Information) clearly asks for details of the applicant, their spouse, siblings and parents. ALL this information is to be filled out, including the details of your spouse/sponsor. If you do not fill in the name of your spouse/common-law partner, you are required to sign saying you do not have either, which would be clearly untrue if you are being sponsored by same.
IMM008 (Generic) is to be completed by ALL applicants, and you now have the option to remove the dependants section from the form if you have none.
IMM008DEP is to be filled out by ALL dependants, whether accompanying or [NOT] accompanying. Therefore, if the applicant has no dependents, only one IMM008 (Generic) is submitted by the applicant with only his/her details.