They'll still tell the story they want to tell, so you don't have to worry about if your character complements theirs unless they specifically so for one of your characters. 

The tiers are split in three, but they are generally broad. 

Low, Mid, and high. 

Low tier encompasses unpowered fights, and maybe just bare minimum magic.

Mid is really wide, and. Encompasses the majority of magic manipulation. Sometimes it split between low and high. 

Then high, which is where you'll find all your top tier, gos level characters. 

If you look at my deposit, most of my characters fall into mid Power. In the split version, Tre'Yan and Dyakuya would be low powered. Kei'taro wouls probably be in the middle, or towards the top of mid.