From the Super Mario Wiki
A Sniffle Thwomp is a type of Thwomp with a cold that appears in Mario & Luigi: Bowser's Inside Story. It takes a little damage after every attack it makes, but if Bowser inhales the ice pack on its head, the Sniffle Thwomp's fever will rise and it will take even more damage.
A Sniffle Thwomp has several attacks. It can jump into the sky and try landing on the character like other Thwomps do. If it sees Bowser in his shell, it'll stop in mid-air and wait for Bowser to retreat. Bowser must withdraw into his shell at the very last moment. Alternately, Bowser can trick the Thwomp by immediately withdrawing repeatedly. If Bowser is fighting, it will sometimes land in front of Bowser and sneeze on him to inflict the Sick status. Bowser has to dodge this move by punching the Thwomp away. Sniffle Thwomp will also faint sometimes and be picked up by a group of White Shy Guys. The Shy Guys walk in a zig-zag path at the character. Bowser and the Mario Bros. must punch and hammer the enemy, respectively, to counter before the Shy Guys ram the character with the Sniffle Thwomp. If a Sniffle Thwomp's eye glints, it will jump up off the Shy Guys to try to smash the character, defend as if it did a regular smash. If the Thwomp was wearing an Ice Pack when it faints, the Ice Pack will stand off to the side on a pair of yellow legs until the attack is complete, or, if the Thwomp is defeated by the counter-attack, the Ice Pack will run away. If Mario and Luigi fight Sniffle Thwomp, it has the same moves, but have to be dodged by their hammer. Instead of the Sick status, Mario and Luigi will get poisoned instead.
Names in other languages
|A pun on Thwomp's Japanese name, dossun.
||Pun on Roca Picuda, which is Thwomp's Spanish name and Resfriado, which means cold (illness)
||A portmanteau of "Thwomp" and "snif" ("sniffle")
||Put on Ecciù (Sneeze sound) and Thwomp