When playing in a Magic: The Gathering format where decks are typically built around a legendary creature, it isnt exactly a revelation to point out that you should include the ability to answer said creatures while building your Commander deck
Card Text: Indestructible As long as your devotion to red and green is less than 7, Xenagos isn't a creature
So, with 210 health, a psychic Pokmon can deal 10 points of damage, but also +30 points for each Energy card attached to two active Pokmon
Brine Elemental + Vesuvan Shapeshifter The block Constructed and Standard deck affectionately known as Pickles used Brine Elemental and Vesuvan Shapeshifter to effectively lock your opponent out of the game
If you do need another card, or want to skip the revealing part, discarding a Vault of Whispers and sacrificing a Dockside Chef puts the necessary card types in your graveyard, and puts Demonic Counsel right in line with Demonic Tutor
Marvel, Elastic Ally Mutagen Connoisseur Mutagen Man, Living Ooze Nantuko Vigilante Pizza Face, Gastromancer Plaxcaster Frogling Prehistoric Turtlesaurus Punk Frogs Putrid Pals Rampaging Yao Guai Raph & Mikey, Troublemakers Renegade Krasis Roalesk, Apex Hybrid Rocksteady, Crash Courser Rocksteady, Mutant Marauder Simic Basilisk Simic Initiate Slithering Cryptid Sliver Overlord Sporeback Troll Stonewood Invoker