i have blue, red, yellow, silver, diamond and sapphire. i always did that to wid eevie, and also the 2 rare ones in ruby and sapphire.
my team in sapphire is blazakin, pikachu, donphan, flygon, kyoge and sharpedo all level 100.
in blue/ did you ever do that cheat. have an item at top of list. go to that old guy let him show you how to catch a pokemon then goe to cinnciber island surf up and down east side of the island. till u coma across thos lv 100 box things. destroy it and you should have 100 or so wotevef your item is. i did this with rare candy and master ball