In defense of differences, Emplaced Weapons are those physically *built in* to the fortification in question. They can be destroyed by damage to the building itself.
Weapon Emplacements are weapons bought (typically) in conjunction with a fortification, but are *stand alone* weapons platforms. The rules are found under Battlefield Debris - and in fact it is fully possible to have a Weapon Emplacement on its own in the middle of the battlefield - whoever gets to it gets to use it, and it grants cover. It has *its own profile*, and can be shot/assaulted *separately* from anything else.
These two things *are* different - they have different rules. Period. Emplaced weapons can not be manually fired via FAQ, but can auto-fire. Weapon Emplacements *do not* have an auto-fire mode, but we're not restricted from using them manually. So go build yourself a Niddy defense line.
That aside... what we have in the book...
Vector Strikes at S6
Full Hive Guard squads
Telekenesis powers (largely on broods of 'thropes to maximize the 2/5 effective powers)
None of these are stellar, but each gives at least a moderate chance of a glance. Pure gunships (ie, the ones that don't need to Hover for a turn to drop off cargo) are already giving up a couple turns of shooting via reserves and movement restrictions, leaving them more limited than people realize.
The best part? Who doesn't already tote Hive Guard? Dakkafexes/Tyrants, and some doods with Wings aren't bad options in general.
Yes, other people can ally in Hydras, which they are likely to do... and then those Hydras will never touch us because all we have to do is *not* Fly with a Tyrant and it can only Snap Fire. Waste of points much?
Powers are only swapped after you've seen your opponent, so if you don't need anti-flyer, take other powers on your 'thrope (or other bugs). We don't have anything to straight drop them by the dozen, but should we? What would the point be if we could just snap our fingers and make them fall?