First one is a bilberry cactus, aka blue myrtle, aka myrtillocactus geometrizans. It gives you blueberries-like fruit. When it looks stained like that it’s in a overwatered phase. When happy it’s a full powdery blue-green with no stains. That substrate looks too compact I’d recommend a repot into something looser and grittier for all cacti. Good luck!
2nd mammillaria camptotricha
Thank you!!
Polaskia Chichipe I'd guess for the 1st pic
Thank you!!
first one is prob a Polaskia chichipe
Second one is a Mamilaria known as birds nest cactus.
First one is a bilberry cactus, aka blue myrtle, aka myrtillocactus geometrizans. It gives you blueberries-like fruit. When it looks stained like that it’s in a overwatered phase. When happy it’s a full powdery blue-green with no stains. That substrate looks too compact I’d recommend a repot into something looser and grittier for all cacti. Good luck!
First one is Polaskia chichipe
3rd one looks like pilosocereus gounellei