Here's a tip for Magicant that's not that obvious: the Groucho/Bonus Swoosh enemies have a chance of leaving the battle on their own and giving a random character a big Exp. boost as they leave. Keep defending and it'll happen eventually.
A lot of people actually recommend running from everything on Mt. Itoi/Holy Loly Mountain, if you've been able to handle everything up to that point. Enemies there are very overpowered, especially on the first visit. If you do fight there, I recommend liberal use of PK Freeze γ if you have it. The final boss can still be handled without the added levels, though.