Using Piranas got me to Stage 10 twice in hardcore but I still lost. Stage 9 is insanely hard as well, with the Piranas deck. It also depends on the hand you draw as, if you got your 3 2 stars and 1 3 star it's GG already. It's frustrating.
I just managed to get the Hardcore star...
Eklore - Isatis - Naja Ld - Wyre - Floyd - Milena - Tolliver - Spade (I'm sure there are better cards, but I think this ones work better to handle Kolos - Oshitsune and to manage to survive the first two rounds)
General tactic was to never use to many pillz early, sometimes just enough to beat 3-4, and also attempt to save the big hits for rounds 3 and 4.
AI drew Noctezuma Cr in the final battle, bu somehow decided the best opening was to hit with Ghumbo using all pillz and fury. Thank god for that!
Finally beat this with Lizbeth - Ironjaw - Raeth - Dr Alma - Hawkins -Parmabarb - Ector - Amiral Coco. Ironically, AI had its worst draw in Round 10 with an Artus - Zapatino - El Mariachi - El Gascaro hand. Got freaking lucky, this was way harder than HQ9. The life gaps are real.