there are a couple ways to get up your stats.

you build up the levels of all the nodes on all positions

Ninja Tools:

You build up your tools and reforge them if they dont have any resistance on them

then there is assist links

because i use these 4 ninja for links:

i get their nature added as resistance as long as i hit the level listed (in total 9+8+7+8 = 32)

all in all its adds up and here is my pos 1 stats

Itachi susano'o is fire based so his weakest is water and i have built back up to 9% positive rather than any % negative

hope this helps and good luck on building it all up