Most sites just tend to copy Serebii. The problem with that is that when Serebii gets something wrong, a lot of other sites do. For example, Serebii says that Houndoom can learn Magic Coat from a tutor in the Frontier Front. When I took my Houndoom to that same tutor, he only offered to teach Houndoom Snore, Spite, Swift, Uproar, and Role Play. Another in that house would teach Mud-Slap, Heat Wave, and Super Fang. The third can teach it Sucker Punch.