Pokemon with HM moves cannot be traded (Fact). But I think I've found a way. Since some pokemon learn some HM moves as eggmoves, you can try trade someone the egg with HM moves. Can someone prove this?
PKMN Black FC: 3568 7240 4459 PKMN White 2 FC: 0004 1159 8660
There is nothing preventing you from trading Pokemon with HM moves, so long as you're doing a normal Pokecenter trade (ie. not Poketransfer or on-the-field IR transfer).
If there is any catch at all (besides it being a normal Pokecenter trade), it's that I think you need to own a second Pokemon with the same HM move. You need to do that to release Pokemon into the wild, at least.
Also, I don't believe any HMs are egg moves per se, but HM transference works the same way as TM transference, so they'll pass down anyway.
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