Entei was resurrected from Ho-oh's powers 150 years ago after it perished in a fire at the Burnt Tower. It became Ho-oh's follower since then, and while trying to protect its master, it was once sealed into the ice mirrors of Mask of Ice along with Raikou and Suicune. Later, Yellow freed them and the three started roaming the land in search of worthy trainers to battle along with. Entei partnered with Blaine, and fought Lugia and Ho-oh at the Pokemon League. It then assisted Silver in chasing Mask of Ice into the voids of time. It disappeared into the lands afterwards.