GSC -In Viridian city gym, there is only Blue/Green to battle you
In seafoam islands cinnebar gym, there is only Blaine to battle you
In Olivine city gym, there is only Jasmine to battle you
HGSS -In Olivine city gym, you only battle Jasmine
In Pokemon heartgold and soulsilver you have to go to the lighthouse and battle then go to cianwood city to get jasmines ampharos some medicine. after that you can go to the gym and the trainers wont BATTLE YOU but congratulate you but technically there will always be gym trainers.