Mixed League vs Dilgar...hmm...my weekly fight for a while...
Partly it really depends on what PL you are playing at. I find the league is a bit weak at raid but good at skirmish and battle.
Patrol - there is only one ship you should ever be taking here. Vaarl. Initiative sink with a 24 inch effect and good stealth to stay alive. You will be tempted by the Tiraca, its a solid patrol hull but dies to easily in anything above raid. Add in the -2 initiative and no abbai hull makes the mixed fleet setting.
Skirmish - Drazi Strikehawk/Warbird pairs have proven their worth to me. The hull 6 seems to be better than the hull 5/2interceptors on the Ikorta. Also the speed of 12, while often a problem for getting shots, means the Drazi can escape a bad position while the Ikorta/Brikorta cannot. If you are playing with the new fighter rules the Brikorta is useful for the two Falkosi though and the precise weapons are a nice addition to the fleet. Only other skirmish hull I would take in a mixed fleet is the Vaarka. Solid scout and has effective weapons if you need a late hitter, plus that lovely high stealth.
Raid - Haltona is a decent hull here if you can get two or more in a squadron. The bimith looks good on paper but rarely seems to make range on a target, even then vs hull 5 your looking at 8ish single damage hits before interceptors. Does that feel like raid level damage? Xill is solid but too fragile vs the double damage beams for me. If you are playing a game with hyperspace available I highly recomend it though. You do have the Solarhawk but only in a big game, too fragile for that cannon. If you do not shoot first you often do not shoot. Battlewagon is a fantastic choice here. Hull 6 with interceptors and a great beam for you PL (almost broken but the boresight fixes that).
Battle - some great ships here. Kaliva, queen of the fleet. Never run her alone, as she needs someone to soak the interceptors for her big lance shots. That she also has a beam and all round firepower is just gravy. Xaak, the perfect Kaliva consort. Hull six cover the only adequate damage/crew but the weapons loadouts and the manuever make this a solid ship. That the slow loaders are precise is the cherry on top. Stormfalcon I truely enjoy, but boresight dependant. One of these is the choice if you only get one battle choice, otherwise take two Kaliva's and call your opponents next of kin.
Carriers - seperated these out as they are really specialty. The Nightfalcon and the Brokados are the ones at battle but I have yet to make good use of them. This is largely due to the way fighters work. If you are going with the new rule the Brokados is a good choice both for the fleet carrier and the command bonus.
War - um...rarely even try here, but I do like the mine cruiser. It deals with things like ISA allied Vaarls very well. It's a specialty, unless you are facing an opponent likely to take hull 4, stealth, or whitestars I do not see the value. With the new fighter rules I may change my mind. The base Tashkat I have not used enough, but feels guns light.
Summation for Dilgar fight -
Patrol - Vaarl (needed for redirect on the boresights, steath initiative sink)
Skirmish - Strikhawk/Warbird pairs or Ikorata (boarding)/Brikorta (fighter)
Raid - Battlewagon, Haltona, Solarhawk, Xill in decending order of desirability
Battle - Kaliva, more Kaliva, maybe a Stormfalcon or Xaak
War - go back to battle and get you some more Kaliva
Ripple