These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Ensemble Darkhorse: Shortly after making his manga debut, Tsun Tsukutsun proved to be rather popular, especially with the girls. Though, having the ability to kick Arale's ass when provoked kind of helps.
Executive Meddling: If Toriyama is to be believed, this is how Arale came to be. Originally the comic was just about Senbei and his inventions. But Torishima insisted that Toriyama create a female lead instead. Toriyama did so intend on just making her a supporting character, but she ironically ended up taking over the whole manga anyway.
Moral Event Horizon: Dr. Mashirito crossed it twice. The first time was when he abandoned Obatchaman for being good, and the second one was when he tried to kill Senbei so way he'd never provide Arale and Obatchaman with Robo-vita-A.
No Export for You: While the entirety of the manga has been translated and released in English, neither of the two anime adaptations have been dubbed in English. It has however been dubbed in Germany, and part of the first adaptation has been dubbed in French as well.
Both the original series and the remake were broadcasted in Mexico and Latin America too.