Ho-Oh

Ho-Oh is a legendary / type Pokemon.

Naming
Its English name is simply another way of transcribing 鳳凰 Hōō, the Japanese word for phoenix.

Biological characteristics
The Ho-Oh is based on the legendary phoenix. Many cultures worldwide hold the phoenix as a symbol of resurrection and reincarnation. A Ho-Oh epitomizes this belief, as it was reborn rising from its own ashes. It also used its powers to give new life to the Raikou, the Entei, and the Suicune, after they perished in Ecruteak City's Burned Tower. It is said that wherever a Ho-Oh flies, a rainbow appears.

Power and Abilities
Ho-oh, based on the pheonix, is a vastly powerful Flying-type Pokemon. It can revive any Pokemon, it is also fast, and has the devastating Fire-type attack, the Sacred Fire.

It also holds an item, Sacred Ash, which is a portable Pokemon Center, reviving all fainted Pokemon in your party to full HP.

Second generation
There is only one in each of the second generation games.

Gold: After receiving the Rainbow Wing from the Radio Director in Goldenrod City, climb to the roof of Tin Tower in Ecruteak City to battle it.

Silver: After receiving the Rainbow Wing in Pewter City, climb to the roof of Ecruteak City's Tin Tower to battle it.

Crystal: After catching Raikou, Entei, and Suicune, meet Eusine in Celadon City's Pokémon Center. Talk to a Wise Trio member in Tin Tower and obtain the Rainbow Wing, which will cause the stairs leading to the Ho-oh appear.

Ho-Oh is yet to appear in Heart Gold: which will appear in the same way as in Pokemon Gold.

Fourth generation
The only way to obtain one in Diamond/Pearl is to migrate one from a GBA version through Pal Park. but it can also be done with action replay. It can also be obtained in the Gold version remake, Pokemon Heart Gold.