Artemis is encountered as the level boss of Mission 3 then becomes part of the boss rush in Mission 14 as Mirage Artemis.
It's very important to no damage this fight as part of your optimal route
This fight is not 100% consistent in NG because Artemis can choose to run away. This means players will have to chase her down and adapt. It's better to save Punch Line after you knock her down from Energy Blast pattern.
New Game cycle
New Game+ cycle
One of the biggest barrier for Nero / Dante / V runs regardless of the category because V is limited to one familiar during that state and he cannot reliably chase down Artemis like Nero. He has to wait for Shadow to approach her before doing anything.
This whole fight depends on your execution of JJC for both versions.
Mission 3 Cycle example
Mission 14 Mirage cycle
It's good to check the Frequently Asked Questions (FAQ) if you have general questions regarding the bosses.