Sacred Beasts

The Sacred Beasts also known as the Five Sacred Beasts (五神, Goshin) are five mythical creatures under the guardianship of the Five Principal Clans.

Summary
Since ancient times, the Yellow Dragon, Ouryuu (Nakiri); the Azure Dragon, Seiyuu (Kushihashi), the Vermillion Bird, Suzaku (Himejima); the Black Tortoise, Genbu (Doumon); and the White Tiger, Byakko (Shrina) have been under the guardianship of the Five Principal Clans with their host being chosen by the Sacred Beasts themselves and those chosen hosts also inherit their names, as well as being the next head of their respective clans. They are noted to have such immense power that even Daiyoukais could not oppose the Five Principal Clans because of their existence.

According to Vali, one of the current hosts of the Sacred Beasts, Nakagami "Ouryuu" Naikiri was noted to be so powerful that not even the Overdrives of Longinus possessors can defeat him, which is proven as even Tobio Ikuse in Overdrive couldn't defeat him albeit he injured him, however, the latter was barely even using ten-percent of his power.

Power and Abilities
Each of the Sacred Beasts has immense power, most of which are based around the elements of their respective Five Elements accessible to their chosen host like the Yellow Dragon's access to the almost limitless earth-based ki flowing throughout the earth known as the "Dragon Veins". Whenever the Sacred Beasts form a pact with their chosen host, they can be summoned onto the battlefield and/or enhance the effects of Shinto Rituals or Eastern Magic spells as first shown by Suzaku Himejima and Genbu Doumon.

Alternatively, they can enhance the power of their host either in the form of their auras as initially shown by Seiryuu Kushihashi or fused with their host as shown by Byakko Shinra.

Trivia

 * The Five Sacred Beasts are based on the Si Xiang/Four Symbols and the Yellow Dragon from Chinese religion and mythology.