Maybe one that involves riding a Pokemon, like how we can ride Gogoats in Lumiose City. Maybe Charge, a move that gives the player a saddle on the field to let it ride it, and in battle it charges at the opponent. Not very creative, but what else could there be.
For those of you who remember Relic Castle's first floor, there were those sand pits. Maybe the new HM could implement standing over loose sand and letting the Pokémon dig out the hidden stairwell, pathway, or pit. In battle it would be a stronger ground move than Dig, but only take up one turn.
I hope there will be some kind of "lava surf" to get across the lava. In Stark Mountain and Reversal Mountain, there was lava. Maybe they could make some alternate kind of Surf with lava. Like Torkoal did in Mystery Dungeon.