Does Blood Moon affect lands that are copies of basic lands such as those made by Vesuva?

Blood Moon reads: 'Nonbasic lands are Mountains.' The key question is whether a land that is a copy of a basic land is itself a basic land. The answer is no — it is not.

A land has the supertype 'Basic' only if that supertype is printed on the card itself (or granted by a continuous effect). When Vesuva enters the battlefield as a copy of, say, a Forest, it copies the Forest's characteristics (name, land type, mana ability), but Vesuva's own card does not have the Basic supertype printed on it, and the copy effect does not grant the Basic supertype either. Per CR 201.2 and CR 305.6, only lands with the Basic supertype are basic lands.

Because Vesuva lacks the Basic supertype, it is a nonbasic land and is therefore affected by Blood Moon. Blood Moon's effect (a continuous effect under CR 613) overwrites Vesuva's land type, making it a Mountain and removing the copied land type (e.g., Forest) along with the associated mana ability.

Example: You control a Vesuva that entered as a copy of Breeding Pool. Your opponent plays Blood Moon. Vesuva becomes a Mountain, produces only red mana, and loses all other subtypes and abilities. It is still named 'Vesuva,' but its land type is now Mountain only.

This applies to any land that copies a basic land (e.g., Thespian's Stage copying a Swamp). The copy does not inherit the Basic supertype, so Blood Moon applies. (CR 201.2, CR 305.6, CR 613.1)