Jirachi

Jirachi's niche in 1v1 stems from the combination of its bulk and Speed tier that allow it to take on multiple top-tier threats, such as Choice Scarf Porygon-Z, Tapu Lele, and Meloetta, alongside its incredible ability in Serene Grace and the two moves that it uses to take advantage of it. Serene Grace is an important factor to Jirachi's success, as it greatly increases Jirachi's odds of winning matchups that it would otherwise struggle in, such as against Tapu Fini, Kommo-o, Crustle, and Hoopa-U, through multiple flinches. Jirachi also has access to multiple coverage moves that aid it in handling Pokemon that can deal with its STAB attacks like Dragonite, Genesect, and Chansey. Unfortunately, Jirachi's STAB attacks aren't perfectly reliable for every matchup. Any matchup that Jirachi doesn't win by raw type advantage or move power alone are often subject to the random chance of whether or not Jirachi lands a flinch or multiple consecutive flinches. The main examples of this include Mega Charizard Y, Magearna, and Zeraora. Jirachi is also not gifted with the best offensive presence, as multiple top-tier threats like Mega Charizard X, Mega Gyarados, and Greninja resist Jirachi's Steel-type STAB attacks and aren't stopped by its coverage without extraordinary luck.