The fact that PPC apps are no longer supported has been known for more than a year (since Lion was released). You need to check into those things before you upgrade. Is your creative suite a PPC app? You could buy an updated version I'm sure.
I am assuming that you upgraded from Snow Leopard? You can "downgrade" back to that, but only with either that install disk or a bootable clone or Time Machine backup. The reason: in order to downgrade, you must boot from another disk and erase the entire drive.
So, if that is what you want to do, then post back and we can provide instructions. If you'd rather troubleshoot, then post back detailing your problems. FWIW, I've been running both Lion and Mountain Lion and have not encountered any problems, so yours should be fixable.
Unfortunately you got caught up in the minor miracle of Rosetta. Originally licensed by Apple when it migrated from the PowerPC CPU platform that it had used from the mid-1990's until the Intel CPU platform in 2006, Rosetta allowed Mac users to continue to use their library of PPC software transparently in emulation.
However, Apple's license to continue to use this technology expired with new releases of OS X commencing with Lion (and now Mountain Lion). While educational efforts have been made over the last 6 years, the fact is that Rosetta was SO successful that many users were caught unaware UNTIL they upgraded to Lion or Mountain Lion.
1. Revert back to your older OS X;
2. Either partition your hard drive or add an external hard drive and install Snow Leopard (with Rosetta) to allow for a "dual-boot" system;
3. Upgrade your PowerPC software or use an alternative programs; or
4. The solution I use: Install Snow Leopard (and Rosetta) into Parallels 7 or 8:
[click on image to enlarge]
Full Snow Leopard installation instructions here:
NOTE: STEP ONE of the instructions must currently be completed on a Snow Leopard or Lion Mac and the resulting modified Snow Leopard.cdr install file can then be moved over to your Mountain Lion Mac for completion of the remaining steps.
NOTE 2: Computer games with complex, 3D or fast motion graphics make not work well or at all in virtualization.