in the trainers tower,people get their strongest pokemon ready for battle.
secret#1: is that all of their pokemon is equal to the level of your highest level pokemon.Example:if u have a level 65 charizard,then all of your opponents pokemon willl be level 65.
secret #2:even though it will be long and add time to your score at the end,you can go back to the first floor after you have designed a type of match and go to nurse joy,heal your pokemon,and go back.it will help you out a lot without using a lot of revives.
secret#3:in certain game packs of firered version,people in the trainer tower have shiny pokemon.these are uncatchable,but when you beat them,they will still be shiny.Example:in my game pack,i saw a shiny espeon(green) in the first double's battle and a shiny seaking(light orange)on the 3rd-5th floors(somewhere in that area)this may not be helpful,but it is always cool to see shiny pokemon.
thanks for reading!!!