Wooden siege engines are going to be useless. Plasma blaster fire will set them ablaze if they even make a near pass.

I think the clone troopers are being heavily underestimated in this thread. Star wars is a large universe and that means that not everything is uniform or consistent, particularly the effects of blasters and weapons. Sometimes blasters just make a spark show and the stormtrooper falls over. Other times a blaster shot will blow huge gaping hole in a clone troopers armor and body. In order to get a good handle on the capabilities of star wars weaponry we need to acknowledge that fiction is fiction and has some inconsistencies. Then we need to figure out what kind of funny damage these weapons SHOULD inflict, given their effects.

Blaster weapons are shown to be remarkably effective in star wars. Taking a shot to any slightly critical area results in death or at the very least incapacitation. Star wars obviously doesn't want to be about gore though, so they leave out the horrifying damage a bolt of ionized plasma would do to a human body. It's not that blasters are incapable of such catastrophic damage/injury, it's that the creators don't want to limit their audience by making it gory or excessively violent.

Since we're here to figure out who would win, it doesn't make sense to go on capabilities that were defined by audience concerns, and not reasonable understanding of what a bolt of plasma should do to a body.

So, trooper weapons should absolutely crush uruks. Superheated plasma flying at high velocity is not going to be kind to metal armor and wooden siege equipment. Consider then that the rifles are fully automatic and that rapid fire blaster weapons (more akin to machine guns than rifles) are seen regularly and you have a lot of nasty hell fire coming at the orks. If they have infinite ammo, I'm not sure the uruks could ever get close enough. Add in artillery and most of them will be dead long before they ever get near the main position.

Ranged weapons beat melee ones. By a lot. This takes it even further by making them space plasma blasters. Troopers take this until they literally starve or run out of ammo or give up.