>>29831936Dhelmise vs. Decidueye is a question of bulk and power vs. a vastly superior movepool. I think Decidueye is actually better off, as stupid as it is that these two are built so similarly.
Decidueye has boosting moves, Baton Pass, two options for recovery in Roost and Synthesis, and some decent utility moves like Defog. It is somewhat faster, too, so it can work better as a pivot, passer, or even wallbreaker. Spirit Shackle is critical as a STAB option and source of momentum, and I could see it ending up as a Baton booster or even go on the offensive itself by using Swords Dance, STABs, and Roost. Shame it doesn't get Shadow Sneak, Agility, or even Tailwind to make up for its lackluster speed, or decent special moves to make use of its wasted mixed offenses.
I don't expect Decidueye to take the competitive scene by force, but I do predict that it has more effective niche possibilities than Dhelmise. Could be totally wrong, and later movepool additions in subsequent games could really help them out.