First one is definitely a euphorbia. I used to have one. Never found out what the species was. ( back then I didn't try to hard.
Second one looks like a trichocereus maybe.
Third one is a tough one. Maybe a species of cholla or autrocylindropuntia?
Fourth one is most likely a species of aloe but it may be worth checking out the genus agave as it could be one of those.
Last one looks like an oreocereus. Most likely oreocereus celsianus.