The requirements are:
Any 5 dark side non—capital ships at 4* or more to get executrix to 5* and then 8 non—capital ships of any alignment at 5* minimum (along with Executrix at 5*) for the challenge itself.
The ships, you listed, are all good. If you add Biggs and Imperial Tie, you are good to go. However, depending on how far you ate with your current DS ships, getting GS' ship to 5* may make the challenge available to you earlier since some of your farms are quite rare in the shop.