After reaching Ops level 10, Ship PvP (the ability to attack and be attacked by other players) becomes available. Bring out our Klingon side and engage with other players!
PvP combos depend on several factors like unlocked Officers, Ships, and Ops level.

You can never go wrong though, with:
1) Epic Kirk - Enterprise Crew (c)/ Rare Spock - Enterprise Crew/ Epic Khan - Khan's Crew

2) Epic Five of Eleven - Unimatrix Twelve(c)/ Epic Khan - Khan's Crew/ One of the below Officers
          Epic Alexander Marcus - Section 31 vs Explorers
          Epic Liviana Charvanek - Romulan Patriots vs Battleships
          Epic Kang - Blood and Honor vs Interceptors

3) Rare Yuki Sulu - Section 31 (c)/ Epic Alexander Marcus - Section 31 / One of the below Officers
          Epic Honorgard Worf - Khitomer's Revenge
          Epic Khan - Khan's Crew
          Rare Gowron- KhitomersRevenge: Marcus Counter
          Rare Martok - Khitomer's Revenge: Kang Counter
          Rare Ba'el - Khitomer's Revenge: Charvanek Counter
          Uncommon L'nar - Romulan Patriots: Anti Klingon
          Rare Krell - Blood and Honor: Anti Federation
          Uncommon Yan'agh - Blood and Honor: Anti Romulan
          Rare Mirek - Romulan Patriots: Anti-Federation