My Super Pershing is optimized for critical damage. Crit rate, crit multiplier and attack speed emblems. Probably better to go with a penetration emblem instead of the multiplier but haven't found a single 3star+ one in a while. There's supposedly emblems with damage as the main stat but I think they were from an event only.

Don't really feel the need for buffing her defense, that's what heavy tanks are for. Though I can see why it would be ok on Super Pershing cause her skill boosts her defensive stats.