What are you think is the Worst ending for the Villain trio? Worst as in what left them the worst off In-Universe, not as in a bad episode. From what I've seen and heard, I haven't seen every series, I'd say the Zenderman ending. Nyaravolta seemingly dies of old age due to lack of elixir, the trio drinks too much turning into babies, the judgement machine explodes, & sends the baby trio into a log going down a path of dangerous rapids. Course, they're all back in spinoffs, even Nyaravolta!
For as goofy and carefree as these shows are, our favorite do-badders certainly have their share of tearjerkers and bittersweet finales, don’t they? Though while they end on a sad note for the trio, they usually end on a light moment, to show that while the series is over, nothing truly ends. Often, like at Yatterman or Ippatsuman, the three part ways, only for the camera to reveal that they haven’t really split up at all and will reunite once again before long.
Others, like Otasukeman, certainly end dour! Our trio decides to sacrifice themselves for the greater good, and launches their ship at the threat to stop it… but before impact, you can see the twinkling lights of four escape units… and after the episode proper, there’s one last wave off from everyone, thanking you for watching the show!
Really, your original example is perhaps the “darkest” and most sad of of the bunch. But at the end of the day, perhaps there’s a bit of a philosphy to it: the Akudaman trio are left as infants, drifting off to parts unknown, yes… but maybe there’s also a chance they will turn out fine, and live their lives a little better a second time around? Alas, I could not tell you 100% the intent behind the ending… only stab in the dark and hope for the best.
What a somber post this post was. Apologies for spoilers to japanese cartoons that are over 30 years old!