Blissey

Blissey shows up on defensive teams as a robust special wall capable of walling threats such as Latios, Thundurus-T, and Volcarona while providing utility with its extensive support options such as Stealth Rock and Wish. Compared to Chansey, Blissey's bulk is worse; however, its ability to use Leftovers means it is far less susceptible to very common residual damage such as sand and entry hazards. Blissey is notably an excellent user of Wish, which can heal up teammates that otherwise struggle with maintaining longevity throughout games such as Excadrill, Abomasnow, Tyranitar, and Forretress. Blissey is an incredibly passive Pokemon and relies almost exclusively on status conditions and Seismic Toss to deal damage, which is a prominent weakness to have when two of the best stallbreakers, Excadrill and Reuniclus, possess high HP and an immunity to Toxic. A large swath of the metagame threatens Blissey out due to its passivity; strong physical attackers such as Terrakion, Mamoswine, and Kyurem-B will swiftly threaten to KO it, and it is unable to threaten them barring statusing them with Toxic or Thunder Wave. Blissey is also prone to being overwhelmed by special attackers; notably, Keldeo has an excellent matchup against Blissey, as it threatens an OHKO with Secret Sword. Pokemon that Blissey is often supposed to check also have tools to overwhelm its titanic bulk, with Latios crippling it with Trick, Thundurus-T setting up Nasty Plot, and Volcarona busting through it with enough Quiver Dance boosts. Blissey is prone to becoming a victim of relentless pivoting loops from the likes of Landorus-T and Rotom-W, and as these threats are often paired with entry hazards and the ubiquitous Sand Stream coming off the likes of Tyranitar and Hippowdon, damage can rack up quickly and leave Blissey at low enough HP to where any stray hit could KO it.