>>58440218That's how bat and bat alike dragons walk on the ground, you can see it in real life, movies and other vidya. Many with this kind of anatomy move like that, done by Yveltal it's quite menacing.
Bats and these kind of dragons are still either mammals or based on them, the wings come from their past quadrupedal ancestors and cousins, they aren't those set of wings that come as a set on the creature's back, it would be hard to carry their weight like most birds do, plus some have membranes on hinder legs too. I think Noivern and Crobat were also shown doing this before.
You might have been confused by how following Pokemon sometimes are allowed to move by either flying/levitating or walking. Sort of like Skarmory & co having both animations.
https://youtube.com/shorts/eZLFDhgJXNk?si=dj9D6ndpLAYioOyR 
