It has
nothing to do with training right/wrong.
It's pokemon
the game, it isn't some real animal that you can care and nurture for it to grow stronger because of some deep seated friendship or bond; it's a bunch of numbers, and the numbers tell me Dialga > Palkia head to head.
If you say something's better because they can do more things like sweep and stall, that's valid.
If you say it's better better of its looks, that's valid too.
If you say it's better since it can beat the thing you're comparing with head to head, then that's just stupid.
Palkia may be a lot better than Dialga in uber teams, but Dialga would take down Palkia head to head.