Giving a trainer more than 6 pokemon

I want to give the last boss of my game more than 6 pokemon, how would I go about making it so only trainers can have more than 6 pokemon (not the player)?

I believe the engine has many checks that prevent this, will it's possible it won't be easy. I recommend you instead made the character battle once again after the first battle ends. The player's hp and pps will be the same so it won't really change much.

Alright, but the thing is I don't want the music to get cutoff, so how do I keep it going during victory, after the battle and into the next battle?