Ummm well i think the first time i gamed was like 4-6 some where around there. I started because my grandparents sent me a Super NES and i started playing Donkey Kong country!!
My favorite character is Marth and i tried him in your same situation except i was using level 9 cpu's. I found that using dodges rolls and especially against Ness counters were extremely useful! use Marth's greater power against them
No items like that is tough but I would like to know with each character How do you get owned like what attacks and such then i might b able to help you more!!