So far there was only one forced exp and that was the battle with plant spiders in evil forest, I had to reset till I got only two of them so everyone got 11 exp and now they are 5 exp short of lvl 2. Bosses as you know, only give AP and since it's lvl 1, you simply have to abuse equipment and abilities heavily.
Also from now on if i want to, I can actually start killing everything as long as I petrify them with quina or later on stop with vivi, since these two statuses cause that monsters give AP but no exp. Later on tho, I will need to get infected by either zombie or virus, depending on the stage of the game.