I'm on chapter 11 right now and I managed to upgrade everything. The enemy only seems to have 1 upgrade that I can see. I take out 4-5 of them every time before I die. I should be able to win now with all my upgrades. Somehow they still manage to grab my princess. Does the enemy get an unfair advantage in battle?
Err... Try using upgraded warrior. There charge attack can 1HKO (Hit Knock Out) them if you use fully-charged attack and they have 6 hearts.
You can also make your fellow red team helpers assist you. Just press up on the directional key. Press left or right (forgot which one) to make a member that is close to you, assist you with carrying the princess. Press down if you dont need them anymore.
No! No! No! No! No! Never use the warrior upgraded! It just makes the game unfair. Sure you can use it when you're not playing against real people, but when vsing real people it just makes the game like " wow we just do the same thing all the time, there's no different classes". What you should do is be the mage and burn some pudding. Burn the villagers when they first pop up, they'll recieve the big pain when their holy shield goes away. Then grab the princess and jump like crazy!
Let evil consume your life into light. Only through evil shall you truly know what goodness and light is. Once you know, you'll want to stay evil for good.