What's up with the evil/dangerous pokemon?

"The spirits burned up in its ominous flame lose their way and wander this world forever."

"Being consumed in Chandelure's flame burns up the spirit, leaving the body behind."

As cute as pokemon tend to be some of them would be absolutely horrifying to meet if one was defenseless.

Whereas some seem to ignore humans or love them, there seem to be some that seem very willing to view humans as a potential food source.