Lots of Gym Leaders and Elite Four members and Champions were difficult for me when I played the games as a kid. When I didn't even know what a base stat was and didn't go into the games already knowing the levels and movesets of all opponents and the locations of all useful items. You know, the intended playstyle and the intended demographic for the games. I have distinct memories of struggling many times with things like Whitney and her Miltank in Gold or Winona and her Altaria in Sapphire, among many other similar cases.