I remember reading that if one of the parents knows an HM, it will be passed down to the offspring. However, I'm aware that Tranpich can't learn Fly normally. I'm expecting Trapinch to not learn Fly, but I just thought I'd ask to confirm.
Prior to Generation VI, if the father knows any moves that are TMs or HMs in that game (and in Crystal, moves that are taught by a Move Tutor) that the baby is also compatible with, it will inherit the move.
No, the Trapinch hatched from the eggs of a Flygon that knows Fly will not hatch with Fly.
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