It’s a common misconception that Raikou, Entei, and Suicune are called the Legendary Dogs, whereas they are in fact termed the Legendary Beasts, and are based on a variety of mythological creatures. Thus, I am freely able to interpret them as big cats if I so wish.
The structure known as the burnt tower was once a beautiful place. When the tower caught fire, three Pokemon perished, engulfed by the flames. After the fire finally went out, a sparkling rainbow came down from the sky. They say it was the legendary Pokemon Ho-oh. Ho-oh used its power to restore the three Pokemon who perished in the fire. People later became to call these Pokemon, Suicune, Entei and Raikou.