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.
Ho Yay: Most of the male cast, but most obviously Artegor and Aarch. They ran off to 'play for the other team' together and when Aarch went back to his own team Artegor never forgave him. He once greeted Aarch by saying "can't live another moment without me?"
Nightmare Fuel: The effects of using the Smog which is basically a metaphor for drugs.
Replacement Scrappy: Yuki gets this treatment in-series to a degree. Especially egrogious since Yuki is actually a stronger goalie in her early games than Ahito ever was early on. Ahito, during the first 3 matches only saved two shots- and one of them was scored at the rebound, the other he didn't even manage to really stop, so Thran had to save it. For comparison, he let 10 goals in.
So Bad, It's Good: The production values, particularly the conventionally animated parts of the first season, which contained a comical amount of continuity errors.
Watch it in the original French language though. The voice acting and script is much better. Especialy condsidering that the cast don't attempt American accents like the (Irish) English dub cast do.
The Woobie: Poor, poor Sinedd. His status as a Smug Snake and minor antagonist cannot be generating enough bad karma to account for all the crap that happens to him. For example: He's a war orphan whose planet was struck by an ice age right after his birth. He was recruited to the Shadows by Artegor as a way of getting back at Aarch, where he absorbed the Smog, which is addictive and and has caused him to collapse screaming on multiple occasions. He narrowly avoided accidentally causing intergalactic war, he got beat up by former goodytwoshoes Rocket, his team was humiliatingly defeated in the GFC only to be brought back so they could be humiliatingly defeated again, and when he lost his Smog no one even picked up the phone to see if he was dead, while his former team-mates fussed over Artegor. Also in Season 3 He is reunited with his parents only to discover sometime later that they are actually just a pair of scam artists out to steal his money.
That time he Almost caused an intergalactic war when trying to prevent others sharing his parents' fate makes him a potential Woobie, Destroyer of Worlds.