- “Okay, everyone, plug your noses. It's about to get funky up in here!”
- —Bad Breath, Belly of the Beast
Bad Breath is a Skylander only featured in the Skylanders Academy television series. Of an unknown element, he possesses a powerful putrid breath to incapacitate enemies. Though he is officially a graduated Skylander, because of his anxiety and gastrointestinal issues, he still has to take part in cadet assignments.
Bad Breath is easily startled or bothered, making him gassy. Despite his unpopularity with the other students, he appears to not mind, but too much stress has caused him to be temporarily put out of duty at the start of Season 1. Unknown to the rest, he sometimes uses empty rooms to burp for as long as he pleases.
Though Bad Breath couldn't care less about the bullying from various students over his weakness, he has been shown to have great empathy, as he abhors other people being mistreated, going as far as to lose his temper when Cy becomes the target of the prejudiced cadets.
Bad Breath can use a particularly putrid breath when burping, with such a powerful smell that it can temporarily knock his targets out and stick to clothing forever. He can also control its duration and strength to sicken enemies far larger than him.
In Skylanders Unite!, Bad Breath was one of the cadets who took their test at the Skylander Games and passed. When Kaos stole The Book of Skylanders on Graduation Day, Bad Breath used his signature breath attack in an attempt to stop him, but Glumshanks shielded his master from the Skylander's putrid breath. He, along with the other Skylanders were then immobilized when Kaos froze The Book of Skylanders solid, which in turn froze all the Skylanders inscribed inside. After the battle, Bad Breath was absent when the Skylanders rescued Spyro from Kaos and Glumshanks. Eruptor revealed that Bad Breath got so scared when Kaos attacked that he kept burping uncontrollably, causing him to leave the Skylander team temporarily.
Though he makes no major appearances for the rest of Season 1, he briefly appears in Beard Science as the only one left in the classroom for Eon's attempts to warn the school about his missing beard, as uninterested as the others. In The Skylands Are Falling!, the Grumblebum is nearly taken away by the world-destroying storm, just barely caught by a building wall when the winds pull him from the ground and a nearby lamp post.
Bad Breath was in class in Spyromania when Spyro interrupted it for a target practice session, though the dragon stopped him from joining in as the breath would've had far bigger consequences.
In Belly of the Beast, Bad Breath was among the cadets who joined along and participated in the mission of rescuing King Pen from the evil Fire Viper. While waiting on the battle plan, he found companionship in Cy, who then volunteered to be Bad Breath's senior advisor for the mission. The battle plan went awry however, causing all of the Skylanders, cadets and Cy to be eaten by Bad Breath. While Team Spyro went to search for a way out of the serpent's digestive tract, the frustrated cadets began to blame Cy for their predicament, but they were reprimanded for their behavior by Bad Breath.
When Team Spyro returned, the cadets expressed their jealousy of Cy's easy ascension to Skylander status to their senior advisors. Spyro shared his experience of earning his Skylander status, and along with Stealth Elf, encouraged the cadets to give Cy and Bad Breath a chance to prove themselves. The group was soon in danger of falling into Fire Viper's stomach, but the serpent's digestive tract was reacting negatively to Bad Breath's noxious belches. Though nervous that he'll be hated by his fellow teammates further, Team Spyro, Kin Pen, Cy and the other cadets encourage him to use his belching abilities. Bad Breath then released massive rancid fumes, leading Fire Viper to vomit the entire team. After making their escape, the cadets worked together with Bad Breath and Cy to defeat the villain.
- Bad Breath is a character created exclusively for the show, as a figure of a non-ideal yet comedic Skylander.
- Bad Breath made the pretzels in the Skylands Music Festival in Pop Rocks, however, because of his constant unhygienic state, Master Eon advised the guests to avoid his food once it was found out.
- In Sheep(ball) Dreams, Bad Breath's skin is mentioned to be furry.
- Bad Breath's powers resemble those of the recurring enemy Malboro from the Final Fantasy series, who are known to have such a putrid smell, shown as the ability also named Bad Breath, that they can inflict multiple status ailments at once and severely cripple their target's skills.
- Unlike other Grumblebum, he only has two eyes and no antlers.
- It is likely that Bad Breath is not mutated like the Grumblebum in Swap Force.