As asked by mpa here is a list of all (working) heroic upgrades in the mod Red Alert 3 Paradox.
Allies:
Assault Striker
Peacekeeper
Icarus
Gaurdian Tank
Units that can't gain veterancy:
Subhunter Frigate
Swan
Horizon
Confederates:
Duster Bomber
Destroyer
Frigate
Units that can't gain veterancy:
Ranger
Dustrunner
M-100
Lee
Note that some units cannot be tested due to the fact that they are unknown or just cause a damage increase (like the Javalin soldier) that heroic would already produce.
