Super Buu was actually the one who dominated Mystic Gohan after absorbing SSJ3 Gotenks. Gohan dominated Super Buu after he had absorbed Piccolo.
That said, to make things even harder to determine, base Gotenks was able to fly multiple circles around the planet at orbital level so fast that he repeatedly intersected his own energy trail in the time that it took Piccolo to go from the Kami's Lookout to the ground level at the bottom of the tower that Kami's lookout floats above, and in DBZ they don't generally leave light trails except as a relatively short range blurring effect that rapidly fades away. To make this even more impressive, going at full speed is generally shown to *rapidly* drain someone's power even in relatively short distances (see Piccolo vs. 3rd Form Frieza), but base Gotenks wasn't even winded.
Furthermore, Mystic Buu (Super Buu after absorbing Piccolo, Goten, Trunks, and Mystic Gohan) was pretty confident that he could chase Goku to any place in the universe that he teleported to, before Buu himself learned how to teleport, but he never really got the opportunity to show if that was a legitimate assessment of his own speed.