No, it is not a glitch. I'm guessing your brother is trying to get a Chingling.
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To get Chingling, you need to breed a Chimeco holding Pure Incense. The baby will be a Chingling.
![Pure Incense](https://archives.bulbagarden.net/media/upload/0/01/Dream_Pure_Incense_Sprite.png)
You can get Pure Incense at the Driftveil Market after getting the National PokeDex, so he should have no problem.