Topic: I need some good concrete advice (Paper Mario: The Thousand-Year Door)

I'm trying to beat shadow queen in paper mario thousand year door. I'm upgrading mario and my partner with the best badges, defense power, feeling fine, exe. The problem is I'm up to the last part of the game so I went back to upgrade because I was not strong enough to beat shadow queen and now I level up while I fight enemies by one star it takes 100 battles to get 3 badges and it's long and tiresome. Is there another way to get more stars faster or do I just have to keep on leveling up by one star till I get to a 100.

I just beat shadow queen. This boss was hard. Finally beat the game. It took a while to train for the boss. The ending was nice and now I'm off to get a new wii game. Either skyward sword or arc rise fantasia.