So let me get this straight,
Mothers rules are 1) MiB cannot leave the island. 2) MiB and Jacob cant hurt each other directly. 3) Mother states that MiB does not ever have to worry about dying.
Exception to rule 1: MiB can leave the island if he finds electro magnetism and builds a wheel to turn and thus must be prevented from leaving physically by someone (mother).
MiB can leave the island if Jacob AND any/all candidates have been killed.
Exception to rule 2: They can actually hurt each other (jacob beats the snot out of MiB a few times) and can kill MiBs physical body OR kill each other indirectly (loophole, using a proxy, i.e Ben and Richard)
Exception to rule 3: If island power gets turned off if MiB is smoke monster, MiB becomes mortal again and can be killed by anyone (kate) or new protector of island (Jack) or a combination of the two or perhaps anyone in the vicinity.
Jacobs rules are 1) a continuation of Mothers rules..MiB cannot leave island, MiB and Jacob cant kill each other directly. In addition 2) MiB cannot kill any candidates
exception to rule 2) MiB can kill candidates indirectly (planting a bomb that if tampered with by candidates could kill candidates).
Additional fuzzy rules: 1) Only the leader can request an audience with Jacob if Jacob deems it worthy.
Exception: If one is forceful enough, you can see him without jacob deeming it worthy and also if forceful enough you can bring someone else with you. (MiB with Ben telling richard)
2) Dead is Dead
Exception: People can communicate with the dead (Hurley Miles) and MiB can pretend to be dead people (possible exception to only being dead people: Walt, Harper). Also Jacob can communicate when he wants to post mortem (jack, MiB, Kate, Sawyer) but only until his ashes are burnt again and dissolve. Or if dead and tried to revive in healing pool, you may come back to life, but you may have some "infection" that turns you into a shadow self with no feelings. Exception: You can be talked out of zombie state and have feelings if speaker is convincing enough (desmond).
3) MiB cannot go over water (that is seen as leaving the island, cant scoot over to hydra island via smoke.
Possible Exception: MiB is seen on the freighter as christian, also Jack sees Christian after he leaves the island and Michael sees libby after leaving the island but these could just be hallucinations.
4) MiB cannot cross over circle of ash directly. However he can force someone out of the ash by dropping a rock on their head forcing them out of the circle. Also if leader of the temple is dead perhaps ash loses its power (ash was made with dogen parts? and therefore loses its power?)
5) Ben and Widmore cannot directly kill each other.
Exception: Perhaps if Jacob dies this rule no longer exists. Perhaps its not a strict rule and just something that was told to both of them. You can also "change the rules" by killing daughters of people. Possible exception: If not real daughter, you can kill them.
6) Whatever happens happens.
Exception: Desmond is special and can alter things/Course correction--saving charlie will die another way.
7) Certain people cannot die until the island (jacob?) is done with them. (open to interpretation)
8) Island is not purgatory
Exception: If you have not been forgiven by island/jacob/god, you are stuck on island after death aka purgatory. (Whispers)
9) If you are banished from the island (either by leader of the others or by turning wheel to get off the island), you cannot ever return to the island.
Exception: If jacob needs you back you may come back. This rule may have been a lie to force issues to get to end result of killing jacob and MiB.
10) MiB can change into any person as long as they are dead, until jacob is killed (not any protector since jack was protector of the island and MiB was still locke) in which case he is stuck using the last person he imitated.
Any other rules I am forgetting? Im just trying to get them all straight into my head. Please make corrections where necessary if i have something wrong.