In dt, u face different starred decks IN YOUR CLASS. That means you can face decks from 24*s to 31*. His deck probably had less stars. As for why you should limit your stars, it's good to have a low star deck cuz you get +1 pts per less star in your deck if u win, meaning if u have a 26* deck and the other guy has a 31* deck and u win, then u get +5 pts (max pts in 5).
For your deck, i suggest Avola, Desmond, Edd Cr, Mona, Oscar, Moses, Prince Jr, Spiaghi/Ace/Ficconaso