Use Idaho (aka Russet) potatoes for the gnocchi. Some stores may label them as "baking potatoes" as well. Don't substitute these potatoes with any other potatoes! Russet potatoes are the best choice here because they are soft, fluffy, crumbly, and fall apart easy. Other types of potatoes are too waxy and contain less starch to achieve the best gnocchi flavor. You can use sweet potatoes to make sweet potato gnocchi, just make sure to check out my recipe and tips for it first. (You can even use cauliflower to make gnocchi, don't miss that recipe!)