For Mashed, one can make a fantastic batch using Red potatoes (leaving the skins on, mind you, for the full “dirty” effect).
Likewise, as an alternative, white sweet potatoes can be coaxed into mashed as well- but skip the cream/milk entirely, and only add a bit of butter and salt. Works best if you bake them instead of boiling them.
Whatever you do, do not mix varieties of potatoes for a batch of mashed. Ever.
For roasted, you can mix and match provided:
- They are the same family (high starch/medium starch)
- They are all the same size