The mode seems like a mix of original G-War with the whole roster & using toons feel, combined with the zone modifiers from G-Challenge events.
As Kyno mentioned, the game gives you a % bar on your characters when you zone in.
You'll want to rotate out between teams to keep them all 80-100%
Good news is, I noticed when I played again the 2nd day all teams were back up to 100% even if they were 70-80 the day before.
And yes, the game is designed to irritate the crude out of you & make you spend.
I hate it & I'm currently approaching 2 years of wasted time trying to recoup 90 days of $$ spent in a perfect example of the Sunk Cost Fallacy. But that's probably a bit off topic, lol.