Omastar

Rock

Omastar is one of Rock's best special sweepers thanks to Shell Smash, allowing it to sweep in matchups like Ground and Steel. Its part Water typing makes it an important asset in the Ground matchup, being able to check Ground-types like Hippowdon, Landorus, and Mamoswine, and it also gives Omastar a helpful neutrality to Steel- and Water-type attacks. With its high Defense, Omastar can easily survive physical hits to take advantage of its ability Weak Armor, granting it +4 Speed when combined with a Shell Smash, which allows it to outspeed fast threats such as Sand Rush Excadrill and Choice Scarf Latios. Unfortunately, Omastar has a terrible Special Defense stat, forcing it to rely on sand's Special Defense boost to set up against most special attackers and leaving it vulnerable to being revenge killed by Choice Scarf users like Nihilego and Gengar. After a single Shell Smash, it still ends up being outsped by common Choice Scarf Pokemon like Nihilego and Victini due to its low base 55 Speed. Its Rock / Water typing gives it a 4x weakness to Grass-type attacks, as well as other common attacking types like Ground, Fighting, and Electric. Omastar is consistently walled by specially defensive Pokemon like Chansey and Mantine and finds a lot of difficulty setting up in matchups outside of Ground and Steel.