Giratina (Origin Forme)

Great League: 4 / 5

A Great League Giratina-O can be obtained by trading one from research and rolling fairly low IVs. Keep in mind that a research Giratina-O may be rare.

Giratina-O brings a unique typing into the Great League; it is a strong Ghost attacker that boasts the defensive qualities of the Dragon-type. Great League often has a greater prominence of Water-, Grass-, Fire-, and Electric-type threats compared to other Leagues, which gives Giratina-O plenty of targets. On top of this, Giratina-O's stats are very reasonable. Keep in mind that it is completely blanked by various Normal- and Dark-type Pokemon such as Lickitung, Umbreon, and Mandibuzz, so pairing it with the likes of Vigoroth or Wigglytuff can help it manage.

Ultra League: 4 / 5

Giratina-O duels its Altered self for dominance of the Ultra League, and with good reason. Its stats are wonderfully set for the Ultra League, with strong damage output from Shadow Ball, and its typing is great. Its two forms have remarkably similar performance, though Giratina-A benefits from the coveted Dragon Claw and extra bulk. It's a genuinely dangerous Pokemon, and in the off chance it gets a boost or two from Ominous Wind, it becomes even more frightening and deadly. Giratina-O also faces competition from the likes of Trevenant and Cofagrigus due to their similar movesets. Common Pokemon like Obstagoon, Mandibuzz, and Umbreon can completely shut Giratina-O down.

Master League: 5 / 5

It's here that the Renegade Pokemon arguably pulls ahead of its Altered counterpart, retaining its sheer power when fully unbound. Giratina-O compresses many roles into one and as a result is one of the most common sight in Master League. It breaks Steel types (other than Dialga), counters Ho-Oh and Kyogre, and checks Mewtwo and Ground-types other than Dragon Tail Groudon. It is the only Dragon-type to maintain a somewhat positive matchup against Zacian. All this while maintaining great neutral damage courtesy of Ghost-type attacks not being resisted by many. Shadow Claw and Shadow Ball being such incredible moves help make up for its single-typed moveset.

Giratina-O is not without flaws, however. Its Ghost-only moveset can leave it walled by Dark- and Normal-types, particularly Yveltal, Zarude, and especially Snorlax. It also generally loses to other Dragon-type Pokemon. Despite these setbacks, Giratina-O has proven time and time again to be a solid anchor to many teams, pairing easily with Steel- and Fairy-type Pokemon. If you intend to play in the Master league, you're going to want a Giratina-O for your team.