I watched this episode/movie in the 90s. It wasn’t a cartoon. The color scheme was dark, as in “Are you afraid of the dark?”. There was a bald scientist (not a protagonist) with an abnormal head (either egg-shaped, or simply oversized), who was able to save his friends (the protagonist group) by consuming a lightning with his head.
Thanks and respect to you all!
Phenomenon – https://www.imdb.com/title/tt0117333/
That reminds me a bit of the last scene in Powder.
It is indeed quite similar, however in my memory the scene had the following important differences:
1. The egghead guy I think wore white scientist robe.
2. The egghead guy consumed the lightning with his head.
3. He did that to save his friends.
4. Everything happened at night.