For a Planeswalker to be your commander, it needs to explicitly say so on the card
Asleep (when inflicted upon a Pokemon, the card should be rotated counterclockwise), Paralyze (when inflicted upon a Pokemon, the card should be rotated clockwise), Poison (when inflicted upon a Pokemon, place a special token), Burned (when inflicted upon a pokemon, place a special token), and Confused (when inflicted upon a Pokemon, the card should be kept upside down)
For example, WotC created Embercleave as the Magic universes version of Excalibur
Fateful Absence is a two-mana White instant that allows you to destroy a creature or a planeswalker, and then the controller of that permanent creates a clue token
As more and more cards have been released into the game, the rare slot has been filled to the brim with all sorts of powerful cards, leading some to top the charts when it comes to price