So a little confusion for me on how NP damage works. Do you need the Overcharge (200-500%) to get the damage on the NP level (2-5) or do you just need to be NP 2-5 to get that damage? I guess in easier terms, does the Overcharge affect your NP damage or just the Overcharge effect?
Level and overcharge are separate. Overcharge may increase damage if the effect applies a buff or defense down prior to the hit. Otherwise only increasing the np level with extra copies of the servant will increase the damage.
So, you get NP5 damage with 100% charge. Getting 500% would only increase the Overcharge bonus effect.
I may say ~80% servants' NP damage are independent to their NP overcharge effect. Only NP level play a the only critical issue.
However, the rest ~20% servants' NP overcharge also affect their NP damage. For instance, Cleo and Ishtar will gain buster-up, Enkidu will gain enemy defense-down, and Musashi will gain NP damage-up. All these effects will enhance the servants' final NP damage when their overcharge reached 200-500%. If not, these buffs only based on charge=100%. So that answer some questions like why Gil's NP1 as a AOE NP still deal very high damage to servants, or double Arash's NP chain deal different damage, etc.
But still, these overcharge buffs are like other buffs from skills (Waver, Merlin, Altera, etc....), which are "bonus" to their np damage, not directly affect the damage from NP level. For instance, Musashi's NP5 OC1 still deal more damage than her NP1 OC5.
NP level is what decides damage. Overcharge has various effects depending on character. You'll have to look the characters up to get any specifics.
The new character profile pages make this a lot clearer, IMHO, because the level and overcharge effects are no longer combined into the same table, which I have to admit confused me when I first started playing...
E.g.: https://grandorder.gamepress.gg/servant/mash-kyrielight
