Its a lot tougher to do these because the manga doesn't spell it out for us, so we sort of have to go on our own.
Rain itself isn't a custom element, its an offshoot of water so it has the same strengths/weaknesses.
Lava is tricky. In the manga someone mentions that they were surprised Kisame was able to take on Roshi by himself considering Roshi was a lava element user and Kisame was a water user. This of course suggests lava is strong against water. On here we've always assumed water will cool down the lava and turn it solid, which isn't necessarily a strength, so it depends on the situation.
Wood again is tricky. I would say its strong against water in the same way as earth is, and weak against lightning because lightning destroys it (seen when Sasuke destroyed some wood with nagashi). Though I wouldn't say its weak enough so that an A rank lightning destroys S rank wood, probably equal rank.
Crystal would be weak against piercing lightning like earth, and strong against water. It pretty much seems like an advanced earth type.
Storm seems like it would be weak against possible wind, and strong against possibly earth (it could destroy it).
Ice is strong against fire, though fire techs of higher level could melt the ice. On here we've accepted that lightning is capable of destroying Ice. Really anything that has a solid physical form can be destroyed by lightning.
Dark release is a weird one. I never saw the movie with it so I don't know much about it. My initial impression is that its not really strong or weak against anything, kind of like normal chakra. Could be completely wrong though.
Swift release isn't elemental so its not weak or strong against anything. I guess if you had to say it had a weakness it would be against doujutsu or earth defenses.
Steel would be the same strength/weakness as earth.
Boil I really have no idea. It was an acidic mist strong enough to burn through Susanoo, so I would assume its strong against earth. Maybe wind techniques would be able to blow it away.
Scorch we don't know enough about. Initial impression is its so hot that it evaporates water, making it strong against water. No idea what it would be weak against.
Senjutsu is just a stronger type of chakra, so it wouldn't have elemental weaknesses/strengths, it would be neutral.
Shadow again isn't element so it should be neutral. Fire can be used to make shadows recede or shoot forward (depending on which direction its coming from).
Bug are non-elemental so again they would be neutral.
Steam could be strong against something like water and weak against something like wind.
Blast really no clue. Not much is known about it yet though its similar to Deidara's clay. Lightning would theoretically diffuse it but I don't know how you would go about diffusing someone's fist.
Sound has some circumstantial stuff. Its strong against water in that if you increase your body size, it will do more damage due to the water in your body amplifying it (like with Choji). But if it hits a wall of water it would be absorbed. Earth would probably be a weakness since its not very permeable to sound waves.
Magnet release would be strong against metals, obviously. I'm not sure what the actual magnetic field would be weak to, but the metal controlled by it would have the same strength/weaknesses as earth.
Sand is weak against something like water because the water will turn it to mud and make it uncontrollable, but pretty strong against most elements. Its good at absorbing impacts like wind and earth, and burns slowly enough to be a good defense against fire. Lightning would be strong against it as well.
Anyways.....that's my opinion on those listed. Though as I said unless the manga tells us which is which its really impossible to know for sure. xd
