Sulfotransferase that utilizes 3'-phospho-5'-adenylyl sulfate (PAPS) as sulfonate donor to catalyze the transfer of sulfate to position 6 of the N-acetylgalactosamine (GalNAc) residue of chondroitin. Chondroitin sulfate constitutes the predominant proteoglycan present in cartilage and is distributed on the surfaces of many cells and extracellular matrices. Catalyzes with a lower efficiency the sulfation of Gal residues of keratan sulfate, another glycosaminoglycan. Can also catalyze the sulfation of the Gal residues in sialyl N-acetyllactosamine (sialyl LacNAc) oligosaccharides. May play a role in the maintenance of naive T-lymphocytes in the spleen 