Steel: 65 species, 10 pure, 55 paired, most often with Psychic (8)
65 of the 1025 species this site covers carry Steel. Defending in Generations VI to IX, the type alone takes the multipliers below.
Immune to
Magnemite#0081
Magneton#0082
Forretress#0205
Steelix#0208
Scizor#0212
Skarmory#0227
Mawile#0303
Aron#0304
Lairon#0305
Aggron#0306
Beldum#0374
Metang#0375
Metagross#0376
Registeel#0379
Jirachi#0385
Empoleon#0395
Shieldon#0410
Bastiodon#0411
Bronzor#0436
Bronzong#0437
Lucario#0448
Magnezone#0462
Probopass#0476
Dialga#0483
Heatran#0485
Excadrill#0530
Escavalier#0589
Ferroseed#0597
Ferrothorn#0598
Klink#0599
Klang#0600
Klinklang#0601
Pawniard#0624
Bisharp#0625
Durant#0632
Cobalion#0638
Genesect#0649
Honedge#0679
Doublade#0680
Aegislash#0681
Klefki#0707
Togedemaru#0777
Solgaleo#0791
Celesteela#0797
Kartana#0798
Magearna#0801
Stakataka#0805
Meltan#0808
Melmetal#0809
Corviknight#0823
Perrserker#0863
Cufant#0878
Copperajah#0879
Duraludon#0884
Tinkatink#0957
Tinkatuff#0958
Tinkaton#0959
Varoom#0965
Revavroom#0966
Orthworm#0968
Kingambit#0983
Iron Treads#0990
Gholdengo#1000
Archaludon#1018
Iron Crown#1023