Ooooh.....
Off-Topic, but..
I have a question, lets say I get Male Grima.
Should I replace Nowi with Hector, or not use Hector at all?
I like a nice balance of red, gray, green and blue. But Hector and Male Grima are really good.
You should train and use both, and use them in different teams, since they are both strong units. Or even use them in the same team; you should also keep in mind that you don't always need to have only one of each colour in a single team. Depending on the enemy team's formation, you may have an easier time using more than one of a particular colour. Like, if the enemy has two red units, you might find two blue units to be more useful than a blue and colourless unit.
I also think this is really the sort of question you should ask when you actually have to make this decision. Since you don't have Grima yet, right now you're better off working with what you do have, rather than speculating too much on a unit you might never get. With gacha games you really just have to work with what you get, since you don't always get what you want.