What does moonstone do in Pokemon Yellow?

In all Pokemon games, including Pokemon Yellow, the Moon Stone works as an evolution stone, allowing certain Pokemon species to evolve.

In Pokemon Yellow, using it can cause the following evolutions:

Clefairy into Clefable

Jigglypuff into Wigglytuff

Nidorina into Nidoqueen

Nidorino into Nidoking

In Pokemon Yellow, Moon Stones are available in the following locations:

Route 2

Mount Moon (x2)

Rocket Hideout

Pokemon Mansion