So...........there's no definitive jedi squad, and also yeah they don't hit very hard. However, that's not their 'thing'. They 'can' though own certain team. For example GG droids. JKR marks GG and then they're history.
Of the relic levels, GMY is possibly the big hitter (other than JKL) so taking him to relic 7 is beneficial.........but of course not for your JML farm. JKR at 5 is fine. I think though, you'd notice a difference with a better relic GMY.
One of the main uses for a 'non JML' jedi is countering SLKR. You probably want to watch some videos on it. For this Old Ben is a necessity. Again, he definitely doesn't need to go beyond the requirements for JML.
So I would say that JKR, JKL, Hoda is your core, which you already have. Then after that it is situational. However, to be competitive at the best levels, you need relics.