Some judges might allow it as either a Plains or a Swamp, but you certainly can't assume that it's safe to play as either without asking
Maybe in a treasure deck it is a bit better than absolute trash
X Porygon-Z DP35 Promo Porygon-Z 26/99 Rare Porygon-Z 7/102 Rare holo Porygon-Z 74/101 Rare holo Porygon-Z BW84 Promo Porygon-Z 66/98 Rare More cards of Ancient Origins expansion Ampharos Spirit Link 70/98 Uncommon Eevee 63/98 Common Porygon 64/98 Common Porygon2 65/98 Uncommon Porygon-Z 66/98 Rare Lugia EX 68/98 Pokmon EX Ace Trainer 69/98 Uncommon Faded Town 73/98 Uncommon
[5] Remember, you need a total of 100 cards
Infamously, when Hogaak, Arisen Necropolis took over Modern in 2019, Bridge from Below was the first card that Wizards banned, in an attempt to slow down the deck
Marchesa, the Black Rose is an interesting choice thanks to her ability to buff Slivers and provide board wipe protection