I'd post mechs, but I have like twenty lists.

Demon Tribe (Devilman): Magdora
Mechanical Beasts (Mazinger Z): Harkenshoot X9
Ghost Mechanical Beasts (Mazinger Z): Poses Omicron 2
Panther Warriors (Cutey Honey): Sea Panther
Mechasauruses (Getter Robo): Giro
Warrior Beasts (Great Mazinger): Gunser
Mecha Oni (Getter Robo G): Mecha Ironclad Oni
Fossil Beasts (Brave Raideen): Drozden
Colossal Monsters (Brave Raideen): Gigar
Saucer Beasts (UFO Robo Grendizer): Buibui
Vega Monsters (UFO Robo Grendizer): Jigajiga
Haniwa Phantoms (Steel Jeeg): Gakki
Monster Slaves (Super Electromagnetic Robot Combatler V): Alpha
Magma Beasts (Super Electromagnetic Robot Combatler V): Mammoth
Beast Fighters (Super Electromagnetic Machine Voltes V): Kanigan
Super Beast Fighters (Super Electromagnetic Machine Voltes V): Kamagurira
Mecha Boosts (Invincible Super Man Zambot 3): Tracid
Battle Robots (Battle Commander Daimos): Grangeiru
Mecha Warriors (Battle Commander Daimos): Daldasu
Megaborg (Invincible Steel Man Daitarn 3): Beltory
Heavy Mobile Mecha (Space Runaway Ideon): Galbo Jik
S-1 Robots (Space Warrior Baldios): Jolern
Connection Robots (Galaxy Cyclone Braiger): Avenger
Deathblack Beastmen (Beast King Golion): Kauman
Mechablack Beastmen (Beast King Golion): Ypsilon
Gyandlar Commanders (Machine Robo: Revenge of Cronos): Clubine
Zoanoids (Guyver: Biobooster Armor): Enzyme
Geister Robos (Brave Exkaiser): Shuttle Lander
Mecha Beasts (Brave of The Sun Fighbird): Anomeras
Combat Troopers (Brave Fighter of Legend Da-Garn): Erbenroy
Armored Beasts (Brave Fighter of Legend Da-Garn): Gracie
Killer Dolls (Brave Fighter of Legend Da-Garn): Albernie
Underworld Mecha (Brave Express Might Gaine): Guyaton
Unlawful Monsters (Brave Police J-Decker): God Whale
Walzc Gears (Brave of Gold Goldran): Biskvito
Angels (Neon Genesis Evangelion): Zeruel
Sargoss Prisoners (Brave Command Dgawon): Zelma Seijin
Zondars (The King of Braves: GaoGaiGar): EI-21
Primevals (The King of Braves: GaoGaiGar): ZX-05
Kyoshin (Neo Ranga): Akasa
Memories (Big O): Big Duo
Devil Beasts (The Devil Lady): Faces
Heterodyne (Dai-Guard): Ice Type
Machine Beasts (Gear Fighter Dendoh): Tangil
Machine Professionals (Gear Figher Dendoh): Bias
Heavy Beasts (Gear Fighter Dendoh): Diver
Dollems (RahXephon): Obbligato
Zeravire (Gravion): Duel
Festum (Fafner in The Azure): Parent Pleidaes Type
Mimetic Beasts (Godannar!!): Type 16
Cherubim (Genesis of Aquarion): Iskuron
Secrets (Eureka Seven AO): Deep Sea Type
Alones (Vividred Operation): Dumbbell Type
Real shame anime these days rarely use monsters of the week.
