Bomber - One good VHF/HF/LF pilot or of course, another bomber.
Gunboat - One good bomber pilot (if there are no missile turrets involved and the gunboat is average) or one bomber one fighter.
Gunship - Do you mean the BH Gunship? If so, one bomber if the gunship's pilot is bad and doesn't have CapMk8. If the gunship has cap mk8 and is a good pilot, expect possibly.. 2-3 bombers to take it down.
The Lane Hacker Gunship is actually pretty terrible. If the pilot is crap, one bomber. If the pilot uses missile turrets, 1-2 bombers.
Light cruiser - One bomber if the pilot is crap, 2 if average.
One Gunboat if the pilot is bad, bomber and gunboat/two gunboats if the pilot is good.
Cruiser - One bomber if the pilot is crap, 2 if average.
One Gunboat if the pilot is bad, bomber and gunboat/two gunboats if the pilot is good.
Pirate cruiser - One bomber if the pilot is crap, 2 if average.
One Gunboat if the pilot is bad, bomber and gunboat/two gunboats if the pilot is good.
Destroyer - Outcast destroyer: 2 gunboats if the destroyer pilot is good. 2 bombers.
Battlecruiser - Possible with one bomber, preferred number would be 2. 3 Gunboats maybe?
Dreadnought - Possible with two bombers, preferred number is 3. 2 Battlecruisers could probably take it down.
Battleship - Possible with two bombers, preferred number is 3. 2 Battlecruisers could probably take it down.
Battlestar - Possible with two bombers, preferred number is 3. 2 Battlecruisers could probably take it down.
Battlestar adv. - Possible with two bombers, preferred number is 3. 2 Battlecruisers could probably take it down.
Carrier - Possible with two bombers, preferred number is 3. 2 Battlecruisers could probably take it down.
Juggernaut - Possible with two bombers, preferred number is 3. 2 Battlecruisers could probably take it down.