Suicune

Thanks to its impressive bulk, good defensive typing, and Pressure, Suicune can PP stall many Pokemon in Ubers, such as Necrozma-DM, slow Yveltal, Eternatus lacking Toxic, Ho-Oh, Blissey, and Tyranitar. The combination of Calm Mind, Substitute, and Scald's burn chance leaves few Pokemon that can offensively threaten Suicune without being stalled out or crippled. Furthermore, Suicune is very potent against passive teams, wearing down the PP of Water-type checks such as Dragon Tail Eternatus, which wall other Water-types like Kyogre. On the other hand, it faces heavy competition as an offensive Pokemon from Kyogre, thanks to its much higher Special Attack and stronger moves. Additionally, Suicune has no reliable recovery, leaving it easily worn down by entry hazards and other sources of chip damage. This also means it is extremely reliant on Leftovers, leaving it weak to Knock Off. Finally, without Rest, Suicune is very susceptible to status conditions.