But then what about swellow, torkoal, or donphan? They all came back in the Sinnoh league to lose...even though swellow was shown to be a major force in Hoenn...
Those were nothing compared to a latios.
Hidden power is a bunch of glowy balls that is easy to animate and is learned by anything with a capacity for TMs short of oddballs like magikarp etc so its no suprise its the go to move in case the animators don't feel like doing anything else.