I can list scenes with new enemies (as seen in PC):
1, 3, 4, 5, 11, 19, 22, 23, 27, 28, 35, 37, 45, 46, 47, 49, 50
54, 55, 58, 61, 80, 91, 97, 101, 110, 111, 113, 121, 124, 126, 129, 132
135, 142, 145, 146, 152, 153, 179, 180, 187, 198, 208, 212, 218
248, 250, 251, 252, 253, 254
As you see, even with import export it takes a little while. Even in scenes without new enemies there may be formation changes etc.
How are you supposed to beat KOTR? I kill him so many times until he uses Vagrant on everyone for 30000 damage, instantly killing everyone.
Use ribbons. Always time your attacks so that you always kill it in 1 hit. Use ultimate weapons. Barret has the best 1 Imo, but if you want KOTR before last mission use Conformer + 4x cut, or kill A LOT of enemis with Vincent and use death penealty for one hit kills. It may inflict stop and/or death on you, but don't bother to protect against it. As long as it doesn't get a turn (by turn I mean when the battle model for the boss actually shows some animation), you should be safe.