What are the good ivs for winter tharja

mine as the opposite stats but as long as you don't have -att or -def you are safe kinda lol. But the best stats I would say +def -speed

Speed is definitely the best Bane. And since she is getting doubled always boosts to either defensive stat is great. HP is an alright bane even if spd is better. Remember she has the highest Resistance stat in the game. So with a Boon she can ploy all day long. Find yourself a RES Ploy and the ATK Ploy seal and you can tank even better and hit harder.

Personally I would prefer a Defense or Resistance Boon and a Spd Bane. So I'd say you got a great boon and an acceptable bane.

I personally think +Res is the way to go. +Res allows for better use of Ploys, is cheaper to build for (since she comes with Iceberg by default), and helps her cover Armor teams' main weakness better. +Def is also extremely good, as most melee units don't have enough Resistance to survive W!Tharja, so she can tank their hits with ease, then erase them on the counterattack.

And of course, -Spd is ALWAYS her best bane. If she gets doubled, she can immediately fire off her special, and you want that to happen against as many opponents as possible. But -HP isn't all that bad, since it doesn't affect her stopping power very much.