i am absolutely s*** at training dudes up to a decent level and end up swearing at my game and ps2 then starting all over again so can someone tell me what levels i should be at the end of each boss o something?i am at the tomb bit on disc one after screwing up on disc 3

The leves of my dudes are:-

squall 25 irvine 15 selphie and zell 18 quistis and rinoa 17