Absolutely. Many trubbish line trainers prefer giving their trubbish citrus peels and sour berries, as the acidity will neutralize the bacteria causing their pokémon’s odor. You may wish to consider leaving out a plate or bowl full of these berries as well as orange or lemon peels for your friend to eat. Additionally giving him a baking soda bath (perhaps by leaving a tray of baking soda out) also works, especially if your friend smells more like vinegar or feet, rather than rotten food. If you can, be sure to put a lid on your garbage to prevent him from eating just anything, and try to encourage him to change his diet slightly. (Non-acidic fruits and vegetables, as well as all dairy products, may make his odor more powerful.)
If all else fails, some air fresheners and air freshening sprays are safe for pokémon such as trubbish and grimer, but be sure to read the label carefully before buying and using it on your friend. Also be sure that if you do use it, only spray it onto his skin; do not let him consume it. For this reason, this is more of a last resort if your town grows hostile to your trubbish friend; it’s a bit too risky to use unless you’ve exhausted all the other options listed above.
Best of luck, anonymous!
The Pokédex According to Bill 