Have all of your fish been living separately since you have had them? And how long have you had them?
Usually the longer the betta is isolated, the more aggressive they become - so adding in adult fish together may cause trouble. But, it may not due to the large tank.
Make sure it is heavily planted (real or fake) to give them lots of hiding places and when being chased they can break the line of sight from the aggressor.
The only concern I have is that you are wanting to place the giants in with a normal.. as long as there is not too big of a difference in size, it should be okay.. but if your common female is quite a bit smaller, she would most likely be picked on the most and could easily succumb to stress.
The tank being that large, and if planted heavily enough, you *may* be able to get away with placing the male in with the 4 giant females. But watch very very closely - some nipping/chasing is normal (for all of them) as they settle their hierarchy.. but if the male or females are being overly picked on by the opposite sex, then I would separate them. Make sure to move them all together at once into the tank, and make sure it's on a day where you don't have plans so you can keep a very close eye on them.
Again, this will depend on how old the fish are, if they have been isolated from the other fish (not seeing them) for a period of time, their own tolerances, the set up, etc. Keeping a single male with multiple females have been done successfully many times - generally not recommended, but sometimes it does work out depending upon a lot of circumstances.
If you notice bite marks on the body, find the aggressor and remove them.. nipped fins are pretty much unavoidable.
I would not place the normal female in the tank with the male at all.
Keep an eye on the plecos, as they grow quite large and 4 would fill up the 55g quite a bit.