Verbal Tic: Likes to add "da-koron" to the ends of its sentences.
Deus ex Machina: All the time, basically. Yatterwan can produce the "Surprise Robots of the Week" when fed special robot dog food, which just so happen to always being the key to defeating the Skull Trio's mecha.
Terrible Trio: The trope image. In fact, the template provided by Doronjo, Boyacky and Tonzler (as well as their expies in the Time Bokan series) are the Trope Codifiers for this trope, at least in Japanese media. The trope was in fact originated by them as far as anime is concerned. They are also much more popular than the heroes within the show's fanbase. It helps that they're not really evil, just greedy (and even if they were evil, they're so inept that they could never successfully hurt anyone anyway.)
Punny Name: His name comes from the Japanese word for "skull" (dokuro).
The Reveal: in the last episode of the 70s series, the Doronbo Gang meets Dokurobei for the first time and they discover that it is an android, and the Dokuro Stone is the real Dokurobei: he really was a skull-shaped stone-like alien who flew over the Earth and got broken into pieces. With his powers, he tricked them into believing the completed Dokuro Stone would have revealed the location of a fabulous treasure, when in reality he "just" needed to be reconstructed.
Self-Destruct Mechanism: Dokurobei's messages to his cronies and the auto-destruct mechanism installed by Boyakki on every mecha he develops, for some reason.
Verbal Tic: He tends to end his sentences with "Bei".
Mascot: Odate Buta (literally means flattery/comment pig), the mechanical pig that appears out of nowhere climbing on a metal palm inside the bad guys' mechas, has become a recognizable symbol of the series. As his name implies, he usually appears in the cockpit of the mecha the Doronbo gang pilots. A coconut tree would appear on the front of the cockpit, to which Odate Buta would climb up and make a snarky comment.
"Even a piggy can climb a tree when praised."
The first poster for the live action movie is just a picture of Odate Buta looking out at the viewer. He's so famous in Japan that it's really all you need to get the point across.