Cores (コア Koa) are a Beyblade Part implemented on December 2001. It was released as a part of the Magnacore System.
Cores are weights contained within the centre of Spin Gears (NEO Spin Gears) and they replace the metal ring found in Standard Spin Gears.
The added weight of either the MW, MG, or HMC is particularly useful for compact customizations; the weight being added in focused in the centre, which will help increase it’s spin velocity. In defense combinations, it will decrease their mobility, making them harder to move and more sturdy. Almost any Beyblade type can benefit from these SG cores.
Magnecores (マグネコア Magune Koa) are magnetic Cores, further divided into South Pole & North Pole.
Magnecore (South Pole) (サウス極 Sausukyoku) repel magnets in a BeyStadium, increasing attack strength and speed, as a Beyblade will move more irregularly and unpredictably.
Magnecore (North Pole) (ノース極 Nōsukyoku) attract magnets in a BeyStadium, drastically increasing defense power as it will become more difficult to push back a Beyblade. However, rotational force will decrease.
Metal Weight Cores (メタルウエイトコア Metaru Ueito Koa) are non-magnetic and only contain weight blocks. They are heavier than Spin Gears and lighter than the Magnecores but other than that, they are no different from the Standard Spin Gears. It can still be found in many Takara Beyblades but Hasbro has replaced it with the Magnecores in most of their Beyblades.
Heavy Metal Cores (ヘビーメタルトコア Hebī Metaru Koa) are the heaviest cores ever released. They are heavier than the Metal Weight Core and made entirely out of metal, improving a Beyblade's defensive power and stability. This is why it is mainly used in Compact and Defensive Beyblades. Despite being released with the Engine Gear System, it is a core meant to be used with the Magnacore System and can be mounted on Blade Bases from that System.