Glad to hear you received the money. Yes, "THEONLYDarkShadow" is fine. =)
It was more the large number of enemies rather than enemies that take more than one hit (although having enemy types that take more than one hit to beat is not a bad idea) that made me think a combo system could potentially be feasible, since there's times that multiple enemies can be hit in quick succession.
A game involving Jenny/XJ-9 could be neat, though I was actually asking if you had any additional goals for this game now that the Sedusa boss fight goal has been reached.
Speaking of which, personally I thought it was going to be a boss fight that Robin would face after defeating Him. Maybe, to make it a bit more special, it could be unlocked by fulfilling a certain condition like destroying every building in every level or by finding the three Egyptian artifacts that Sedusa used hidden inside certain buildings like the milk cartons are, with one artifact in each area.
For an idea of how the boss fight itself could work, it occurred to me that a mechanic that hasn't been used yet in a boss fight is the super giant mechanic. Perhaps the boss fight could involve Robin having to avoid Sedusa's attacks until she can find milk cartons since Sedusa would only be vulnerable to Robin's attacks when she's in a super giant state? Since the state is temporary, this creates a gameplay loop where Robin is going back and forth between avoiding Sedusa's attacks and dealing damage until she's defeated, with Sedusa's attacks becoming faster and more intense as the battle goes on. For a bit of extra aesthetic flair, maybe each of Sedusa's phases take place in each of the different areas, giving the impression that her and Robin are fighting all across Townsville? If you want to have cutscenes for it like the other bosses, you'd have a great opportunity to depict a Sedusa shrunken back to normal size (or even tinier if you wished) looking up at a super giant Robin, making Robin look really huge.
If you like that idea for the boss fight, or have any feedback on it, I'd like to hear it. =) I tried to come up with something that could make for a neat boss fight while also not taxing your animator/programmer too much. Oh, and you're welcome. I look forward to the boss fight. =D