Rock-type Pokémon stand out for their great defense to physical attacks, however, this type is tied with the Grass-type as having the most weaknesses, with five, and Pokémon of this type are not very fast. Also, some Rock-type moves don't have great accuracy.
All Fossil Pokémon are of this type. Their fossils preserve enough material genetic to be worked with to bring them back to life, but, it can be known, that the Rock-type was very abundant. They also have unique combinations to Pokémon of the present.
The Rock-type is commonly combined with the Ground-type, so they are usually confused, although they're not the same. Even in the anime, this confusion has been present, saying that Rock-type Pokémon are immune to Electric-type attacks.
They're strong against the Bug type because a rock can easily crush an insect.
They're strong against the Fire type because rocks can trap a fire, and the fire disappears easily if rocks are thrown on it. Additionally, rocks are not flammable.
They're strong against the Flying type because in ancient times birds were hunted with the use of stones, and throwing a stone at a bird can kill it, hence the term "You can kill two birds with one stone".
They're strong against the Ice type because stones and rocks can shatter ice with ease.
They're weak against the Grass type because the roots of trees and plants make their way through the ground, and if there's a rock, they destroy it.
They're weak against the Ground type because sandstorms erode rocks and earthquakes destroy structures made of stone and concrete.
They're weak against the Fighting type because fighters destroy rocks as part of their training.
They're weak against the Steel type because steel is harder than stone and can break it.
They're weak against the Water type because water erodes rocks.
They're resistant to the Normal type because regular people cannot split rocks.
They're resistant to the Poison type because rocks are non-organic and are thus unaffected by poisons.
The Rock-type is tied with the Grass-type for the most weaknesses (5).
However, if both are combined, the weakness outcome only comes out as 4.
The Pokémon Trainer Guess toy states that the Rock-type is called the Jewel-type.