But why?/Unite License 22

But why?

So, as you can see from this list, this is few of the TM's that Houndoom learns in Scarlet and Violet. Can you spot the odd one out?

Why is Houndoom able to learn the move Rain Dance, the one move that weakens all of it's Fire-Type moves for a few turns?

Just-bu-bu-but why? Why?

Unite License 22

Speaking of Houndoom, here's the 22nd Unite License I made which you can tell is for Houndoom. I feel ashamed making another Unite License

Again, you may have to zoom in, in order to see the words better