Game Difficulty 4-5

[Rose]

I have beat the stages on all difficulties in the sense that I achieve victory. However, I am unsatisfied that I have "beat the game" seeing as I consistently cannot beat the boss on wave 24 and/or 25. Has anyone found a strategy that seems to work best? I haven't found anything for any map yet.

[achecopar]

I'm having trouble at wave 9 on difficulty 4... lol