Lets be fair to the point because even Moon's attack failed too.
They're going against higher levels of enemies. They have to fail. They need to fail in order to show - storywise- how dangerous the enemies are. If they just knocked off Tellu without a second look, then what would be the purpose of the upgrades later?
Also, Chibiusa is a Senshi-In-Training. Her power is gonna be weaker than Moon's and the others.
The Outers are powerful, and they have to be for what they're doing and what they're stationed as. So yeah, they're gonna save them because that's their princess(es) and they don't want them to be hurt.
If you noticed how each witch of the Witches five introduce themselves and their power level it makes utter sense. Especially with the levels of how strong the bad guys are.
you have Master Pharaoh 90 at the top, Mistress 9 is next, then Tomoe, Magnus Kaorinite next. Those are the top four powerful bad guys this season.
Under them? The Witches five who are noted to be the most powerful group that the former two (Kaorinite and Tomoe) created.
Power order (Strongest to weak)
Cyprine (Ptiol) at Level 999
Tellu at Level 404
Viluy is Level 202
Eudial is level 78
Mimiette is Level 40
(Honestly, the Inners could've defeated Mimi on their own but circumstances)
My point is, they're not ineffective, it's just that their opponents are stronger than what they've fought before. Therefore necessitates the
need for power ups later. Otherwise, what's the point of said power ups?
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Personally, My favorite thing of SMC is that it makes me empathize with Chibiusa. Usagi is a competent leader with no sliding back in personality and she is actively growing with her experiences. Her and Chibiusa's relationships are amazing in this because they don't bicker all the time and over petty stuff. They actually get along and have mother-daughter moments more and more.
Also, Mamoru is not a punchline narrative, and is involved in every facet of the story even if he's only there for two minutes, he's shown and is involved somehow. They all treat him with respect and value his opinion and no one believes he's cheating every other season. It's lovely. (Also his attack and powers coming into play more. ;n; )
Luna is amazingly well done overall too, because her personality is one of caring and she's not a jerk or plays on Usagi's insecurities as a joke.
There's no 'panty shots', fat jokes, or anything really uncomfortable about this version.
Mamoru and Usagi's relationship is beautiful.
Uranus apologizing for confusing them.
Hotaru!
Literally, everything.
Only thing I'm kinda Meh, about is the attacks aren't as interesting as they were before and the Transformations aren't as interesting either. I liked the CGI of the first two seasons because it happened at a different angle, so it felt fresh and new. If they had kept that different angle approach, I'd be happy. Same thing with the attacks. Different angle/way of doing them makes it very interesting. I'm just glad the girls get to use newer attacks in season three and Venus's Wink chain Sword is amazing.