Plastic bowls are also not recommended because they tend to scratch very easily from the paws and teeth. These tiny scratches are then perfect breeding crevices for bacteria. And even though you may be great about cleaning your Pug's dishes on a regular basis, it's best to avoid having to deal with germs at all.
Since these are very lightweight, they often slide all over (or tip), which can lead to a bad eating experience for a puppy or dog. And if your Pug will be home alone, you'll want his bowls to be super sturdy and essentially tip-proof.
The second issue with sizing, is that us humans tend to fill up whatever dish or plate we have in front of us. So, it's not uncommon for owners to feed their Pugs too much food at meal time if the bowl is over-sized. And with this breed, it's not uncommon to be a bit overweight.
Though, if you have an aggressive eater, you may also want to obtain a bowl mat or choose bowls that are within a base, which keeps the dishes in place and also is great for catching any spills and messes.
You can opt for a slow-feeding bowl itself, which is designed to promote slow eating by means of an inner protrusion that displaces the food. Or, if your Pug loves his current bowl, you can opt for a portion pacer. These are stainless steel balls, appropriately sized, that sit within the dish to displace food. As a dog noses at his food, the ball moves around.