I found some posts for 3.5e but there's not much information on incorporeal creatures attacking corporeal ones in the rules as far as I can find. It's pretty clear in the universal monster rules how attacking an incorporeal enemy works if your corporeal but not the other way around. Some lines in the description seem to imply that it can attack but it also says it has no physical effect on its surroundings which makes me wonder how it actually attacks.
An incorporeal creature’s attacks pass through (ignore) natural armor, armor, and shields, although deflection bonuses and force effects (such as mage armor) work normally against it. Incorporeal creatures pass through and operate in water as easily as they do in air. Incorporeal creatures cannot fall or take falling damage. Incorporeal creatures cannot make trip or grapple attacks, nor can they be tripped or grappled. In fact, they cannot take any physical action that would move or manipulate an opponent or its equipment, nor are they subject to such actions. Incorporeal creatures have no weight and do not set off traps that are triggered by weight.
It says its attacks ignore most forms of ac but it also says it cannot move or manipulate an opponent or it's equipment.
It says they can move things but poltergeists and a few other incorporeal enemies can via telekinesis.
A poltergeist has no method of attacking apart from telekinesis. This ability functions as the spell telekinesis, with a CL equal to the poltergeist’s Hit Dice (CL 3rd for most poltergeists). A typical poltergeist has a ranged attack roll of +3 when using telekinesis to hurl objects or creatures, and can use the ability on objects or creatures of up to 75 pounds. If a poltergeist attempts to hurl a creature with this ability, that creature can resist the effect with a successful DC 12 Will save. The save DC is Charisma-based.
So at least in the case of a poltergeist, they can only attack indirectly.
A haunt can use an "incorporeal touch attack" according to a few if it skills but the description of the incorporeal ability seems to imply incorporeal creatures can't interact with the environment.
Alternate Form (Su) A haunt's natural form is that of a translucent image appearing much as the person did in life. As a standard action, it can alter its form so as to appear as a floating, luminescent ball of light (possibly being mistaken for a will-o'-wisp in this form). In this form, it cannot use its Dexterity damage attack or its malevolence attack. It retains its incorporeal form and can make an incorporeal touch attack that deals normal damage (but not Dex damage). A haunt remains in one form or the other until it chooses to assume a new one (as a standard action). A change in form cannot be dispelled. A haunt cannot change forms while using its malevolence attack (that is, while possessing a host).
Comozant wyrds can latch onto stuff and use their whip attack to hurt stuff.
Plasma Form (Ex) Although incorporeal, a comozant wyrd can't hide inside solid objects. It must start its turn attached to the outside of something that's solid and of Small size or larger, or else it takes 5 points of damage. Anyone attacking the wyrd must either take a -4 penalty on the attack roll or resolve the attack against whatever the wyrd is attached to as well.
Lightning Lash (Su)
As a standard action that doesn't provoke attacks of opportunity, a comozant wyrd can shock any creature or object within 30 feet to which it has line of effect, dealing 2d8 electricity damage. The wyrd can choose for this damage to be nonlethal. If the target is also affected by the wyrd's illuminating flames, it is stunned for 1 round (Fortitude DC 16 negates) and the flames are dispelled. The save DC is Charisma-based.
My main point of confusion is the lack of clarity in the description of the incorporeal ability, it says they can't move stuff but multiple incorporeal enemies have telekinesis and thus can move stuff, they can't grab it with hands per say but they can still move stuff. If they can't touch things directly how come Comozant wyrds can latch onto stuff despite being incorporeal. If it can latch unto stuff how come it can't trip or move stuff? Are these exceptions? Does magic like stuff such as lightning lash not count as interacting with the environment? If they can interact with the environment when why can't they move things? There's too much stuff that contradicts itself.
Can someone point me to a clear statement on the rules regarding how they do so.