I don't know about the accessories, but #49 in the bestiary is Fallen + Soul. In the Northern Ruins (where you upgrade the Masamune) there are two battles with the Fallen and Soul enemies. Anyway, if you wait a bit, they will merge into one, creating #49. Also, you only have two chances to do this. After which, you have to do it in a New Game +, etc. Also, someone on the GameFAQs boards had a great idea for getting Magus and entry #195 at the same time. Because you have to be strong enough to beat Lavos, probably best on a New Game + game. Anyway, save right before you fight Magus, fight and defeat him and then go directly to Lavos via the bucket at the End of Time, defeat Lavos and then save after the credits. Make sure that you don't save between defeating Magus and beating the game. The reason being is that when you save after beating the game, it saves all your bestiary info, etc (i.e. you'll have entry #195) now, but it also takes you back to the actual point in the game you were at before fighting Magus. Thus, you can get him to join. I've heard it works, too, but haven't done it myself yet.