First ones

I am a tad unsure how they level in this game thought usage. I mean I keep all of mine on the same usage count so they all grow at the same rate, but even with all of them at the same rate they all show as level 0 in the monsterpedia, but what really seams off is when I am using them they all have a different level ranging from 68 to 99. Does that level for them actually impact anything? Also they are all listed as E rank when you look at their details. I know their stats all start as E- rank and grow to S+ at their peak of power. But does their numerical level actually impact anything or is it just a pseudo level?

It’s just a pseudo level