If you're thinking of pedantry as being overly concerned with minute details and rules:
* Informal
* Relaxed
* Casual
* Spontaneous
* Unpretentious
* Practical
* Down-to-earth
If you're thinking of pedantry as being excessively academic and showing off knowledge:
* Natural
* Humble
* Unpretentious
* Practical
* Down-to-earth
* Easygoing
* Unsophisticated
If you're thinking of pedantry as being overly critical and fault-finding:
* Tolerant
* Forgiving
* Understanding
* Compassionate
* Open-minded
* Empathetic
Ultimately, the best opposite of pedantic depends on the specific context and the specific aspect of pedantry you want to highlight.