There r combos in it, if u really want to find the full potential of the combos try thr trial challenges, there hard but if you can pull them of there insanly powerful, but they will take time.
If anybody is having trouble wiv the arcade mode on the hardest difficulty and the time attack and survivial challenges i offer you this advice use zangief and lariat your way to victory as the computer has real difficulty dealing wiv this, wiv the exception of cammy who can b a problem as her cannon drill seems to b the only move which can counter the lariat, but in this situation i advise that you keep low and block and just kick, and if you get a chance when shes close use the piledriver, this is the best tactic ive found.
Regarding the arcade mode use zangief again but on the hardest difficulty put it on 1 round and timer at 30 secs and you'll complete it, another character which can b a sod is seth on the arcade mode but follow the rules ive said wiv the round and the timer, and when u get to seth deal some damage and 4 the rest of the fight just block, as usually seth will just resort to useing his sonic boom and just block and let the timer run out.
This idea may seem like cheating, but its the easiest method i've found but in the end its your desisions if u want to use it or not. If you want to see what the hardest computer players are like just go on versus and battle it out.
Hope this helps anything else dont hesitate to ask.