Chō Dossun (超ドッスン, Hyper/Super Thwomp) is a powerful, spike-less Big Thwomp who functions as the "final boss" of Mario and Yoshi's RPG adventure in the last chapter of Super Mario-kun volume 7. Its statistics state that its level is "invincible" and its HP amounts to 100,000.
After a long search, Mario and Yoshi find the Star Hana with which they can cure the Mura Mura citizens and Luigi from the influenza tontonbū-gata. Mario goes to collect it, but Chō Dossun emerges, yelling at them. Mario first tries diplomatically to obtain the flower by explaining the situation, but Chō Dossun does not care about the fate of Mura Mura. Angry, Mario attacks it with a cape twirl, in vain. Yoshi obtains a Music Box to make Chō Dossun fall asleep, but only Mario is enchanted by the music. Mario then takes a big pencil with mines and uses them as spears, angering Chō Dossun. Furious, Mario pulls out a syringe with the influenza tontonbū-gata inside and injects it into Chō Dossun, turning it into a harmless pig, winning the battle, and takes the Star Hana.