(Missable!)
Entries for an enemy are unlocked by seeing them perform a certain move, performing a certain move against them and even receiving an enemy attack. Please note that a certain move requires you to die, and thus you cannot get this trophy during your play through for The Devil Made Me Do It.
Thankfully, an enemy has its move counted for you in the status menu (for example, in the Marionette page, the count will be 4/7, meaning you have four of the seven moves recorded) so you only need to check up on the guide given here:
Devil May Cry Enemy Files FAQ by Tai Chi
https://www.gamefaqs.com/ps3/646887-devil-may-cry-hd-collect...