Leviathan Mist claims it's possible to get the Charm Bangle while not gaining a level in his Perfect Stats guide.
My party is Terra, Edgar, Setzer and Sabin. All of them are lvl 6 and need 384 xp to level up, which means they have not gained even 1 xp point towards leveling up. Cyan, Locke, and Gau are basically unavailable as although they are on lvl 7, they are all very close to leveling after the Mag Roader sequence.
As far as I know, every fight must be fought and won to accumulate enough points: three battles with 1 Commando, one battle with 1 Mega Armor, and one battle with 3 SP forces. Mega Armor gives 350 xp, Commando gives 252x3 xp, SP forces give 200x3 xp. Grand total 1706 xp, which is 426 xp per character.
Mathematically, I don't see how it can be done. Either one of the battles can be skipped, or at least one of the enemies can be killed without netting any experience (something I don't know how to do, if it's even possible), or possibly with a glitch that I don't know of.
Found out how on Lufia_Maxim's guide for the Game Boy Advance version.... which is amazing (the guide, I mean). Muddle one of your characters and use a smoke bomb during the animation so the Commando will RUN from YOU! And it counts as a defeat, w/o xp. Awesome.
How in the world are you suppose to rely on your character using a smoke bomb while muddled? There's got to be at least 100 other commands it could choose from. --- Well I can help you without witchcraft, pills, and molestation. But it won't be easy.