Tartarussian and Plutonian are bosses which appear in two different scenario. Tartarussian serves as the boss of Mission 2 in Lucia's route, while Plutonian serves as the boss of Mission 8 in Lucia's route and Mission 12 in Dante's route.
Tartarussian fight with Lucia's route in Mission 2 is very important to get her route going. Because, she must upgrade her swords into Lv2. Plutonian for the most part is situational that depends on your Devil Star stock and DT gauge for characters. The main goals to keep in mind during this fight is to :
NG+ Note: Round Trip / Aerial Cross + Flame Heart trivializes this fight.
These enemies has extra defence against Firearms. They also have ability to negate it's damage by rotating their Iron Balls, which happens more frequently in DMD. Therefore, you have to engage them strictly in melee.
Both of these bosses will either throw iron balls if at distance, or swing them if you get too close. If the fight goes too long, Plutonian can summon Agonofinis, or cause electric beams to shoot out of the walls.
FireArm negate (Applies to Majin Fir balls too)
If it weren't for the random blocks, this fight is completely scripted. There are 3 steps to this fight :
Lucia is extremely strong at that point of the run. The DT gauge build depends on your movement throughout Mission 8. There are 4 steps to this fight :
Lucia has to strafe per hit because Tartarussian / Plutonian are one of the bosses that makes her float above the boss per hit for some odd reason. This will make her Aerial Cross hit a lot less. Ending this fight with SHOWTIME!! is very ideal because it helps your currency route a lot for the end game missions.
Dante only fights Plutonian. His cycle is situational because of his route so, he can either :
Million Stab against this boss has much different approach than Furiataurus :
It's good to check the Frequently Asked Questions (FAQ) if you have general questions regarding the bosses.