A large number of units in GC are both faction and planet specific (and require the necessary land or space buildings). While not a complete list (and lacking easter egg units), here is a partial list of where units can be created in Galactic Conquest:

StarViper, Keldabe, Krayt-destroyer, Mandalorian Commando - Mandalore
Vulture Droids, Tri-Fighters, Pinnace, Nantex, Ginivex - Geonosis
Providence , Lucrehulk, Techno Union starship, Probe droid, R3-Slicer - Mechis
Techno Union fighter - Utapau
Recusant, Munificent - Mechis, Hypori, Saleucami, Mustafar
Corellian Frigate, Corellian Destroyer, Corellian Battlecruiser, Barloz, CC-7700 - Corellia
T-wing - Fondor
Rebel Carrier, Preybird, Liberator, Dauntless - Sullust
Assault Frigate, Dreadnaught Heavy Cruiser, Iblis/Peregrine - Rendili
Mediator, MC90, MC80, MC75, MC40, MC30 - Mon Calamari
Bulwark - Fondor, Hypori, Saleucami, Mustarfar, Mechis
Delta-7, ARC-170 Fighter - Ord Mantell
Dark Side Adept - Korriban
NovaTroopers - Carida, Bastion
XR-85 - Mechis, Bastion
Tauntaun Troopers - Hoth, Ilum, Polus, Alzoc III, Mygeeto
AAT, Battle Droid, Droideka, Super Battle Droid, Enforcer, Hailfire, MTT, STAP - Geonosis, Mechis, Hypori
Tyrant, Venator, Corona Frigate, A-9, Dominator, Escort Carrier, Lancer, Mandator, Legacy, Procurator, Sovereign, Star Galleon - Kuat
TIE-X1, Avenger, Defender, TIE-Droid, TIE-Phantom, TIE-Raptor, TIE-Scimitar - Corulag