My Houndoom is having problems with… Well, farts. That’s very problematic since the smog doesn’t only make my house smelling bad, it is toxic! What can I do to avoid this problem?

Switch to a different brand of kibble. Sometimes, kibble brands can be a bit of a lottery with pokémon. Some types of kibble have absolutely no ill effects on the pokémon that eat them; others … result in the exact problem you’re describing. You may wish to offer your houndoom a bit of wet food now and then too.