How does battling work?

When someone attacks you, is it their ATK against your DEF?  Does it change during each player's turn, or is it always using the DEF stat?  I assume that the player attacking is the one "going first"?

who goes first depends on who has higher agility
that said, attackers have a slight agility advantage

when a monsters attacks another monster, their atk stats are being measured against your defence stats, there are also random inaccuracies so that each atk or defence varies a little even if the teams remain the same. some time an attack might miss its target altogether

and as i was saying agility determines which monster attacks first. if you are being attacked and survive the first attack, then it is your monster's turn to attack the enemy, and it works the same way, your monsters atk stats are being measures against the def stats of the opposing monster.

so in a battle (whether you are the attacker or the defender), assuming you dont die in the first hit, all stats of your form is being used

It seems the higher the defense is compared to the attack. The higher chance if a miss.
Dodge roll is then at partly determined by the disparity between attack and defense?