Kartana

Kartana has a huge Attack stat, a good Speed stat, and decent physical bulk, allowing it to outspeed common Pokemon in the 1v1 metagame like Mega Gyarados, Mega Tyranitar, and Tapu Lele and hit them hard. It has access to setup moves like Iron Defense and Swords Dance, which work with its high Speed to take out Pokemon like Mega Metagross and Zygarde-C. Despite this, Kartana is weak to Fire and Fighting, meaning frequently used Pokemon like Mega Charizard X, Mega Charizard Y, and Mega Lopunny can easily counter it. It has horrific special bulk and is easily OHKOed by even resisted attacks from some of the most common special attackers in the metagame, such as Choice Scarf Porygon-Z, Kommo-o, Magnezone, and Meloetta. It also finds itself outclassed by bulkier Steel-types like Magearna and Mega Metagross.