Space Marines would mostly be Fighting/Steel (with LotD being Ghost/Steel, Librarians being Psychic/Steel, and Assault Marines being Flying/Steel or Flying/Fighting)
Necrons would largely be Dark/Steel or Dark/Electric or Electric/Steel. But a bunch of them would be Steel/Bug, of course, and then you have things like the Wraiths (Ghost/Electric) and honestly the Forgeworld burrowing asshole is like Electric and Steel and Ghost and Ground.
Mechanicum would do some kind of Normal-Steel-Electric combination, with varying things swapping in weirder Types.
Orks are some kind of Grass-Psychic-Fighting combination, with different Orkspects getting different types (Stormboyz = Flying/Fighting, Burnaboyz = Grass/Fire etc)
Daemons are probably all over the place, with Khorne being Dark/Fighting, Nurgle being Dark/Poison or Ghost/Poison, Slaanesh being something in the Dark-Psychic-Ghost triad and Tzeentch having some combination of Dark-Psychic-Ghost-Fire
Sisters are mostly Dark/Fire or Steel/Fire, depending on whether you value "fuck psykers" or "clad in armour" as a bigger part of their identity. Saint Celestine is Flying/Fairy, because flying and because she's the shiny heroine of shining niceness and also runs up and kicks Dark types in the scrote.
Eldar probably vary based on Aspect, with everything being a unique fucking snowflake. So you have Normal (Guardians), Fighting (Avengers), Ghost (Wraith___), Psychic (Seers), Fire (Dragons), Flying (Hawks) and so on. Maybe even shit like Bug for Scorpions (because you fuck them up with flamers or air strikes and you deploy them to fuck up special characters like psykers).
Dark Eldar are Dark/
EldarPoison. Many are Dark/Flying.
I don't care enough about Tau to go over them.
Tyranids... I actually went into too much detail ages ago, when I was pondering doing a romhack.
Ripper: Bug (Swarm/Schooling), evolves into Sky-Slasher
Sky-Slasher: Bug/Flying (Swarm/Schooling)
Termagant: Bug/Ground (Simple), evolves into Gargoyle
Gargoyle: Bug/Flying (Keen Eye, H: Speed Boost)
Hormagant: Bug/Fighting (Simple), evolves into Ravener
Ravener: Bug/Ground (Infiltrate, H: Super Luck)
Spore: Poison (Levitate), evolves into Bigger Spore
Bigger Spore: Flying/Poison (Aftermath), evolves into Mycetispore
Mycetispore: Flying/Poison (Aftermath, H: Shield Dust)
Mawloc: Ground/Bug (Regenerator), evolves into Trygon
Trygon: Ground/Bug (Regenerator), evolves into Trygon Prime
Trygon Prime: Ground/Psychic (Regenerator/Telepathy)
Zoanthrope: Psychic/Bug (Levitate), evolves into Neurothrope
Neurothrope: Psychic/Bug (Levitate), evolves into Maleceptor
Maleceptor: Psychic/Bug (Sturdy/Serene Grace)
Gene Stealer: Dark/Bug (Infiltrate), evolves into Broodlord
Broodlord: Dark/Psychic (Intimidate/Dazzling), evolves into Lictor
Lictor: Dark/Bug (Camouflage/Illusion)
Venomthrope: Poison (Effect Spore/Gooey), evolves into Malanthrope
Malanthrope: Poison/Psychic (Adaptability), evolves into Toxicrene
Toxicrene: Poison (Sturdy/Filter)
Tyrant Guard: Bug/Rock (Multiscale/Marvel Scale, H: Magic Bounce), evolves into Hive Guard
Hive Guard: Bug/Steel (Skill Link/Guts, H: No Guard)
Pyrovore: Fire/Bug (Aftermath/Flame Body), evolves into Scythed Hierodule
Scythed Hierodule: Poison/Bug (Filter), evolves into Barbed Hierodule
Barbed Hierodule: Bug/Poison (Rough Skin/Bulletproof)
Biovore: Fighting/Bug (Skill Link/Mega Launcher), evolves into Tyrannofex
Tyrannofex: Bug/Poison (Sniper/Mega Launcher), evolves into Exocrine
Exocrine: Electric/Bug (Sniper/Mega Launcher, H: Galvanise)
Haruspex: Bug/Dark (Strong Jaw/Long Reach), evolves into Dimachaeron
Dimachaeron: Bug/Ground (Speed Boost)
Tyrant: Psychic/Dark (Telepathy), evolves into Flyrant
Flyrant: Psychic/Flying (Technician)
Screamer-Killer: Bug/Fighting (Filter/Tough Claws), evolves into Wreckerfex or Dakkafex
Wreckerfex: Bug/Fighting (Adaptability/Tough Claws)
Dakkafex: Bug/Fighting (Technician/Sniper)
Hive Crone: Flying/Poison (Tough Claws), evolves into Harpy
Harpy: Flying/Bug (Technician), evolves into Harridan
Harridan: Dragon/Bug (Levitate)
Warrior: Bug/Fighting (Telepathy), evolves into Prime or Shrike
Prime: Bug/Psychic (Prankster)
Shrike: Flying/Psychic (Speed Boost)
*Legendary: Old One Eye: Bug/Steel (Filter)
*Legendary: Swarmlord: Psychic/Fighting (Super Luck)
*Legendary: Lurker in the Swarm: Bug/Flying (Prankster)
*Legendary: Parasite of Mortrex: Psychic/Bug (Regenerator)
*Legendary: Death Leaper: Dark/Bug (Intimidate)
*Legendary: The Red Terror: Dark/Ground (Strong Jaw)
I put too much thought into Pokemon-related things