Relicanth

At first glance, Relicanth looks like an inferior version of Kabutops or Omastar. However, Relicanth has a few niches, mainly its access to Rock Head. With Rock Head, Relicanth can abuse STAB Head Smash to great effect, punching holes in just about any Pokemon. It also isn't that bad defensively either; 100 / 130 / 65 defenses aren't half-bad for a Rock-type Pokemon.

However, Relicanth is in the NU tier for a reason: base 90 Attack is disappointingly average for a Pokemon with such a potent attack. To make matters worse, it doesn't have a single move in its arsenal with which to boost its Attack. Relicanth is also slow, base 55 Speed means that faster Pokemon can easily attack Relicanth before it can retaliate, though Rock Polish fixes this to an extent. Furthermore, Relicanth has a limited movepool, making it fairly predictable, and a poor typing, which grants it weaknesses to common types in the RU metagame, such as Electric, Fighting, and Grass. However, don't underestimate this bony fish--it has just enough power to rip through unprepared teams.