Make your board indestructible, then turn around and prevent all damage to yourself

XY Single Pack Blister [Dragonite] Dragonite Collector's Pin 3 Pack Blister $309.00 Dragonite EX Box $263.13 Kanto Power Collection [Dragonite EX/Pidgeot EX] $493.26 Kanto Power Mini Tin [Dragonite] $36.03 Dragonite Dragons Tin $65.93 Checklane 2 Mini-Pack Blister [Dragonite] $24.99 Dragonite Dragons Tin (Walgreens Exclusive) $52.73 Dark Dragonite #5Holo Rare $240.97 Dark Dragonite #15Rare $92.41 Dark Dragonite - 15/109 (EX Team Rocket Returns) #15Holo Rare $125.49 Dark Dragonite (22) #22Rare $38.95 Dark Dragonite (5) #5Holo Rare $180.45 Dragonite #2Holo Rare $189.66 Dragonite #18Rare $15.29 Dragonite #5Holo Rare $30.59 Dragonite #83Holo Rare $21.44 Dragonite #96Holo Rare $4.09 Swellow (Delta Species) #40Uncommon $1.67 Lickitung (Delta Species) #19Rare $2.37 Pinsir (Delta Species) #9Holo Rare $24.11 Ampharos (Delta Species) #1Holo Rare $53.22 Quagsire (Delta Species) #21Rare $14.73 Nidoqueen (Delta Species) #7Holo Rare $30.31 Pupitar (Delta Species) #59Common $0.40 Mantine (Delta Species) #20Rare $2.25 Gligar (Delta Species) #16Rare $2.23 Seadra - 037/101 (Delta Species) #37Uncommon $1.22

This is a 60 card, elite golgari (green/black) desert ramp MTG deck
Acorn cards get to adventure into the design space of caring about name and art as well as using things like outside assistance
The concept alone sells it -- a Transform Pokemon rendered in that signature purple blob form, ready to become anything on the field
Pushing your deck above 60 (or 40) cards makes it harder to find key cards, increases the risk of "mana flood" (drawing only lands, so you have nothing to cast) and "mana screw" (drawing too few lands, so you can't cast any of the spells in your hand), and makes it more likely that you'll draw unplayable hands