Can you pop into Endless Corridor and see what your HP is and how much you can heal per turn? There are a lot of factors to consider for Goemon. Odds are, you won't be able to burst him down. You'll need to be able to tank the fight, maintain your heart orb matching, AND put pressure on him to pick away at his health.
Oh man, can't even fit 3 RKs + Siren with my team cost. I could put a Super King Metal Dragon instead of the Siren or I can get rid of an RK and put in a black, red or blue ripper, horus, CDK, that's all the options with above 1400 hp anyway..