These are the ones that I’ve missed so don’t fret and think that these are super rare enemies or something cuz there’s every chance you’ve already come across them!
Flangonzola: This was found in sunny weather in The Archylte Steppe (Plains of Eternity) near the vicinity of the red flowers close to Long Gui. It’s a white flan and it’s considered a rare monster. Nothing else much to say about it since the group that I ran into went down pretty fast. ^^
I enabled Battlemania and Encounter Master to get it. However, out of the billions of monsters I fought in the area, I only found the Flangonzola twice. 
Malebranche:I found this thing in stormy weather in The Archylte Steppe (Clearwater Marshes) near the far west end close to the wide chasm. Looks like a brown-coloured Wladislaus. This thing can be trouble since its attacks can deal strong physical damage and remove the buffs on a party member. It also has some crazy attacks that can chop down a member’s life with wound damage by a great deal. What’s worse is that it slaps on Slow as well.
Ugh. I totally went into this unprepared but luckily I had a Sentinel in 2 of my paradigms. Didn’t know it was weak to magic and kept relying on my COMs. XD Managed to 5-star the fight somehow though. ^^ Got no spoils though. 😦
Hmm. It seems annoyingly rare. I’ve gone through about 10+ battles already and it has yet to show up again. I even managed to run across a Fomoire while waiting for Malebranche to appear. 😛
Swampmonk: For some reason, I’ve never found this thing before. Apparently, it’s in the marshes of the Steppe as well and shows up during rainy weather. Ah. Found it. I got a group of 3 with a Mewmao thrown in. Of course, I took out the cat first. And while the monks went down fast, they DO have a skill called Power Spritz that bestow them with a crap ton of buffs. Since my party of pretty high levelled, it wasn’t much of an issue. ^^
Anyway, I ran into some to the northern part of the middle area of the Clearwater Marshes. Actually, it seems to appear quite a bit around the patch of dry land close to the middle too. :O
Tezcatlipoca: BAWWW. Missed this bugger on my trip through the final dungeon. Now I gotta redo the entire thing again JUST for it. Sigh.
Is it just me or do I not have to touch as many blocks on a second pass through this dungeon? Took me a while to realize this though. ^^;
Edit: FINALLY! DONE WITH THIS DAMN SIDEQUEST!
Went to collect my new Fragment Skill from the Mystic at Serendipity. When I went to turn on Field Killer, I saw this:
I think this really only affects players doing the 100 consecutive GREAT!s thing.
Ooh. I unlocked Mobile Mog a while back but never went to get it. ^^; Whee! *throws the moogle around Academia 4XX and watches the crowds of people follow it wherever it goes! XD*
koukoupuffs 
haha “annoyances”
sorry to bother you again, i do have a question about the monsters, do they appear 2 chaos bahamut and 8 caius ballad on the monster log?
’cause on the bestiary of the guide they appear and also fromoire’s fist and g– fist but they don’t appear on my monsters killed… is that a problem? D:
thanks again
I think you DO need to have every single Caius and Proto fal’Cie entries to complete the quest. It should be noted that the quest is not possible to finish before the main storyline since there are some rare monsters that pop up after it like Raspatil. And if the multiple Caiuses and Proto fal’Cie are also needed then you have to do the Paradox Endings for several locations too. 😦
Fomoire and its damnable fist usually appear along the western and southern edges of the Steppe marshes in rainy weather.
Some of the monsters I have killed are not marked as “checked” in the log entry. Even the monsters I have tamed. Is this a bug or something or am I doing something wrong?
I believe they become checked if you get all the information of the monster.