Grouping the villain groups, which were robots, demons, space aliens, etc. Suggested by a pal. I might be wrong in some of the older ones.
Hundred Violent Demon Tribes (Turboranger)
Youkai Army Corp (Kakuranger)
Made into aliens in Power Rangers.
Saima Family (GoGoV)
They were really from hades and inspired by horror movie monsters.
Ashu Clan/Questers (Boukenger)
They were also youkai.
SPACE ALIENS (9)
Reconstructive Experiment Empire Mess (Flashman)
Silver Imperial Army Zone
Space alien pirates.
Londarz Family (Timeranger)
Criminal aliens and robots, made into 'mutants' in Power Rangers.
Aliens based on insects.
DIMENSIONAL BEINGS (4)
Vader Clan (Denjiman)
From another dimension, they were 'twisted.' Made into aliens in PR.
From a dimension that was split from ours during dino times.
The New Empire Gear (Bioman)
Baranoia Empire (Ohranger)
Gien and his mecha (Timeranger)
EARTH-BOUND TRIBES/SUPERNATURAL (10)
Black Cross Army (Goranger)
Secret Society Egos
Ancient civilization lived in shadows.
Tailed-People Clan Jashinka Empire
Humans evolved from Reptiles, underground.
Bandora's Gang (Zyuranger)
Didn't know where to put them. They lived on the Moon but were from Earth. Bandora was a witch and the monsters were created from clay. Her crew could have been aliens, unsure.
Gorma Tribe (Dairanger)
Tribe with chi powers.
Gordom Civilization (Boukenger)
Dark Shadow (Boukenger)
Group with animal-based kung fu style wrapped with the undead.
Dragon/Lizard mutants, Ryuuwon used to be human.
I don't know what to call them because they were humans that became evil and had a space shuttle and their monsters were mixture of 'Chaos', the fiery remnants of life in wastelands, and brain core.
Black Magma (Sun Vulcan)
Humans that made monsters mixture of mechanical and organic.
PLAIN OLD CRIMINALS
Criminal Organization Crime (JAKQ)
I might be wrong in some of the older ones.