Taken about 2 years but finally got all badges. Grandmaster score chaser was the hardest one for me. Had to complete with 7 challenges to get it. Doom slayer was tough too but when I got the right build I absolutely smashed yog for it.
If you use weapons above your strength they become much less accurate. If you use armour above your strength your movement speed and I think evasion go down drastically.
Edit: Also your attack speed is lower with a weapon that is too heavy.
I think the warrior is the easiest. He is simple, with his seal you can take one armour upgrade with you to your next armour, which is great to survive the earlier levels. That way you can effectively use armour that would normally require 12 or 14 strength with 11 or 13 strength respectively.
The Mage is nice because you can just pump the first upgrade scrolls into his staff to get a good weapon. You just have to be more careful about being hit.
