The Combaticon's Face–Heel Turn. They tore the guard apart. It's also notable, because Bruticus hasn't been the best combiner (Dreamwave, and the later seasons of G1 saw to that). But now, he's a huge beast outfitted with armor, and built from military vehicles, and he kicks ass.
In Battle-lines, Lyzack gets one. She's the Token chick on the Decepticons, gets no respect (Demeaned by Starscream), and is reduced to a server instead of a warrior (as she was built as a support mech). She also has several depressive traits. Near the finale she takes on Magunm, the Elite guard leader, and cuts him down, defeating him.
Thunderclash then takes her out with a single punch before she can finish him.
For all his skills and manipulations, Deathsaurus is defeated by the Cloudcuckoolander Sprocket, who jumps on his back, asks for a "Zap"-Pony ride, and shoots him point blank in the chest.