Check the link below :-
Base repo should contain all the filesets , they are available in the AIX install media itself.
e.g. bos.adt.base.18.104.22.168 for AIX 7.1
Abhinay: please open a ticket for this, there are some known issues for patching AIX prior to 8.2 SP4 and a specific hotfix. Please mention my name in your ticket.