Pokemon HeartGold

[Namine]

I believe the elemental punches are in battle frontier (so at the very dead end of the game.) Old GSC games elemental punches were much earlier on in Goldenrod, but now they got scaled back and it's much more costly to learn them too.

As for Gardevoir, much better for her to use psychic. I don't think she can learn zen headbutt anyway. Elemental punches are also all physical now. Gardevoir has always been much more of a support type though with access to wish, dual screens will o wisp and healing wish. If you really want her to be a sweeper, then shadow ball, thunderbolt, focus blast, signal beam and trick (for using choice spec) are you best options.