So, I'm not sure if the manga is going to go over this stuff or not, but I'd like to explain a few things that were skipped over here since I see some questions/complains here in the comments.
First off, Gobuta didn't actually dodge those attacks at all. He "accidentally" dodged them although it looks like he is being treated as less of a comedic character here. His part in the LN broke up the tension of the moment for a bit but I guess it wasn't needed in the manga.
Second, the revival of Charybdis isn't exactly what is happening here. Rather, these are poorly made copies of Charybdis made from the magicules Clayman was able to retrieve and fuse into an artificial soul core. When the core is fused with a living body the magicules explode out and corrupt the body turning it into a cheap knockoff of Charybdis but with notably the same magic dispersion skill and hyper regeneration.
Finally, to explain Benimaru's seemingly ease of killing the Charybdis clones. First off, they hadn't been fully formed so their magicule count (and thus their magicule defense) wasn't at max yet. And their max is around 30% of the real Charybdis so Benimaru hit them when they were at about 10% of the original's power. Next you have to remember that by this point Benimaru is actually stronger than Rimiru was when they fought Charybdis originally. Keep in mind that Benimaru was able to beat Phobio, the third strongest majin in all of Yuurazania, in a straight up fight. Also, Black Flame (and by extension Black Lightning) are derivatives of Veldora's magicule based skills and thus are more easily able to overcome magicule resistance. And finally, Benimaru's Black Flame isn't completely a direct attack as he using a combination of Black Flame and a Barrier skill to encapsulate the Black Flame into a small sphere concentrating the heat. Without heat or flame resistance it is a devastating skill that punches far above it's weight in Magicules.
Edit: Oh, right I forgot another big thing. At this point Rimiru has gone through the Harvest Festival and the True Demon Lord Awakening so all of his named followers got a secondary power-up at well. There are other explanations too but I think that'd be spoilery for things I'm sure they'll put into the manga.
Second, the revival of Charybdis isn't exactly what is happening here. Rather, these are poorly made copies of Charybdis made from the magicules Clayman was able to retrieve and fuse into an artificial soul core. When the core is fused with a living body the magicules explode out and corrupt the body turning it into a cheap knockoff of Charybdis but with notably the same magic dispersion skill and hyper regeneration.
Finally, to explain Benimaru's seemingly ease of killing the Charybdis clones. First off, they hadn't been fully formed so their magicule count (and thus their magicule defense) wasn't at max yet. And their max is around 30% of the real Charybdis so Benimaru hit them when they were at about 10% of the original's power. Next you have to remember that by this point Benimaru is actually stronger than Rimiru was when they fought Charybdis originally. Keep in mind that Benimaru was able to beat Phobio, the third strongest majin in all of Yuurazania, in a straight up fight. Also, Black Flame (and by extension Black Lightning) are derivatives of Veldora's magicule based skills and thus are more easily able to overcome magicule resistance. And finally, Benimaru's Black Flame isn't completely a direct attack as he using a combination of Black Flame and a Barrier skill to encapsulate the Black Flame into a small sphere concentrating the heat. Without heat or flame resistance it is a devastating skill that punches far above it's weight in Magicules.
Edit: Oh, right I forgot another big thing. At this point Rimiru has gone through the Harvest Festival and the True Demon Lord Awakening so all of his named followers got a secondary power-up at well. There are other explanations too but I think that'd be spoilery for things I'm sure they'll put into the manga.