As one of the pillars, and also the 3rd generation, Nataku most definitely has immense firepower.
Giovanni's strength does not lie in some sort of fire power, despite being a 2nd generation. He is however one hell of a scientist.
If Konro did not use too much of his fire power, he would probably be among one of the strongest characters in the series.
Tamaki is more known for being a fan service character rather than being a fighter like Maki for example.
There is very little information about Kayoko's strength. I can only assume that since she is one of the captains of the Special Fire Force, she must at least have some skills.
Obi is incredibly resilient and tough to crack thanks to his muscular body and mental strength.
And after having one of the most respected figures in the Fire Force, here we have I think the one of the least respected.
Being a 3rd generation, Paat is able to buff a certain person's heat resistance.