I might get some of these wrong or miss some so uhh yeah-

None
Start - "One left."
Kill - "None left."

Ninja
Start - "Running cannot save you."
Kill - "All that speed and yet you still get cut down."

Cowboy
Start - "You cannot bring justice."
Kill - "Just like him."

Adans
Start - "I know your secret."
Kill - "Im more of a monster than you are."

Wrath
Start - "A mindless brute."
Kill - "Your legend ends here."

Lunatic
Start - "A cheap imitation."
Kill - "My LV is stronger."

Bonehead
Start - "Smiley trashbag."
Kill - "Time to join your brother."

Illuko
Start - "You wont shine for long."
Kill - "Even gods fall to my blade."

Flower
Start - "Asriel?"
Kill - "Coward."
Special (from flower) - "Chara? is that you?"

Royalty
Start - "Ive killed you a thousand times, a thousand more wouldnt hurt."
Kill - "Another kill to the list."