I can't speak for other elements, but for Thunder, it seems okay-ish. I'd rate many slightly lower or higher, but about there.

Well, I don't really agree with the assessment of Athena, rated S there. Sure, Athena is AMAZING... ... against Water. So much to the extent that those who struggle against Water content (Fire mains, Water mains who want to fight Water Accessory quests or something if I've understood right) might want to pick her up with a Miracle Ticket. Not always, but might.

But Thunder mains? Do you really need a powerhouse that works only against Water element, the one thing you're already strong against? I... doubt it. As such, would you really rate her an unconditional S like Mammon...?