All I hear about in history of Vikings is during the 800s where they invaded Britain. They had their typical iron helmet, wooden shield, spear, chainmail and sword.
What did they wear during the 1200s to 1400s when Europe was full of kettle helmets, knights in shining armour, crossbows and pikes? Did they still fight primarily as infantry in shield walls? Or did they just copy the Germans, French, English?
I've just re-compiled the relevant material in: Swedish medieval armor.
As for the later fate of shield wall, you can also check in: When did the Shield-wall strategy die?