Dynamax Blissey

One of the absolute tankiest Pokemon in the game, Blissey is a must-have for any serious Max Battles teambuilding. Thanks to its seemingly infinite HP pool, Blissey's Max Spirit provides unrivaled healing for its allies, taking most Pokemon from the brink of fainting to full health in two or three casts. Healing isn't all that Blissey does - its unmatched bulk and one weakness makes it the best generalist tank in the game. To give an idea of how tanky Blissey is, a not-very-effective hit against Metagross or Blastoise do more damage than the same neutral attack does to Blissey. To top this all off, Blissey even possesses a Fast Attack with a 0.5 second duration, Pound, enabling it to rapidly charge up the Max Meter.

Blissey does have a few paltry downsides. Its Normal typing doesn't resist anything bar a double resistance to Ghost, so some Pokemon can outperform Blissey with enough bulk and/or double resistance. Additionally is its high HP / middling Defense stat spread makes it not a particularly great user of Max Guard, as Max Guard provides a flat amount of HP for shielding. Blissey isn't particularly great at keeping its shields alive to constantly redirect single-target attacks from bosses, which can leave glassier teammates vulnerable to getting oneshot. Nevertheless, Blissey makes up for these minor inconveniences by being naturally insanely tanky and providing unbelievable healing.