Off the the top of my head there's:
Clive Vs
Aang (FFXVI Vs ATLA)
*Both have mastery over the elements plus can freely switch between them in battle (ironically Aang initially hated fire but fire is Clive's go to element).
*Both are survivors of a destroyed nation (Grand Duchy of Rosaria and The Air Nomads), thus carrying a gigantic emotional burden.
*They eventually discover they played a part in the destruction of their homeland (Clive unwittingly destroying it as Ifrit and Aang abandoning it when they needed him the most) which left them guilt ridden for a time after being initially unaware of the circumstances.
*Their homeland was also invaded by a imperialistic power that's closely connected to dragons (Holy Empire of Sanbreque and The Fire Nation).
*Both are charged with ending a war that's engulfed multiple nations for years yet both have different approaches to fulfilling their prophecy intentionally or not (with Aang eventually accepting his role as the Avatar while Clive constantly refusing to accept his role as Mythos to the point Odin's powers had to be forced upon him).
*Both are connected to a godly entity that granted their position (Ultima and Raava) yet these entities are complete opposites in terms of their views on the world and especially their views on humanity.
*Both initially couldn't control their transformations and as a consequence caused major damage while being afraid of it (Ifrit and Avatar state) since it felt like they were observing the destruction from outside their bodies.
*Both are prophesized beings with the power to reshape/balance the world (Mythos and Avatar) yet while only a few people know of Mythos in Clive's world, very few people haven't heard of the Avatar in Aang's world.
*Both have a close bond with an animal companion who is more than capable in battle themselves and has powers too (Torgal and Appa).
There's a few other connections (West Vs East cultural inspiration) plus the fact their markings/brand plays a part in defining their character but that's the general gist of it.
Clive Vs
Yugo (FFXVI Vs Wakfu)
*Both are skilled users of magical powers (Aether and Wakfu) yet the magical energy their use turns out to have a high cost.
*Both are the last (known) survivors of an invasion (the Sanbreque invasion for Clive and the Mechasm invasion for Yugo).
*Despite their vast mythical powers, their favoured weapon of choice is the sword or blade which they put to good use against a wide variety of mystical, mechanical and monstrous opponents.
*Both are connected to their brothers who can reincarnate/resurrect (Joshua the Phoenix and Adamaï the Dragon).
*Both would suffer the lost of both friends and families alike early on in their several years journey (Most notably Cid for Clive and Tristepin for Yugo).
*Both would travel from kingdom to kingdom learning more about the true nature of the world while trying to make peace between warring nations (which naturally doesn't end well).
*In the end it's discover their fate is far more grand than their can ever imagine and essentially become "god" after several years of adventures (Mythos fulfilled Clive and god-king Yugo).
There's also the fact one is from a anime inspired western animation while the other is from a western inspired JRPG (spectacle fighter hybrid) for contrasts kek!
Clive Vs
Ramza (For a same verse twist)
*Both are upper classmen who ended up as mercenaries after a tragic burning related event that left them outcast and cost them the lives of their loved ones (Clive losing his brother and father and Ramza losing his adoptive brother and sister) yet unbeknownst to them one of their loved ones actually survives (the brothers; Joshua and Delita).
*Both got betrayed by a family member who was response for the death of their father's (Clive getting betrayed by his mother; Annabelle who sold out her husband to the empire while Ramza got betrayed by his eldest brother Dycedarg who slowly poisoned their father to death).
*Both get caught up in a "game" of political turmoil between nations which eventually lead to war across the land with their surviving brother playing things in the shadows, with Joshua secretly trying to help Clive and while Delita is secretly helping himself while manipulating Ramza.
*It's later revealed everyone (including the nobles, commoners, aristocrats, players, etc) are all just pawns for a much greater evil (Ultima) and naturally most people don't believe either Clive or Ramza.
*Both end up being "branded" in different ways with Clive literally being branded thus gets treated like a slave by most people across the land while Ramza is branded a heretic by the Church for killing a cardinal (who turned out to be one of the demonic servants of Ultima) thus is constantly on the run.
*Both ultimately just want to protect their younger sibling (Clive's brother Joshua and Ramza's sister Alma) after Clive discovers Joshua is alive and Ramza discovers Alma got kidnapped by the Church.
*Both end up with frankly massive arsenals with Clive and his Eikon abilities and Ramza with his Job classes, which they put to good use into defeating Ultima and saving the world.
There's also the added fact they both parallel each other with both successful stopping Ultima but Clive couldn't save his younger brother Joshua (but was able to save Jill and create a better world for all people while succumbing to the crystal's curse himself) while Ramza did save his younger sister Alma and go on to have new adventures (at the price he had to slay his eldest brothers; Dycedarg and Zalbaag, the former becoming one of Ultima's demonic servants and latter being brought back as an undead after being killed by the former), showing both had quite the bittersweet journey to reach their respective conclusions.
Other MUs:
Clive Vs
Dante or
Dante (For the inspiration connections since FFXVI straight up has DMC 5 moves and other DMC references plus the obvious inner demon, complicated brotherhood and red/blank motif style connections however Dante has better opponents).
Clive Vs
Eren (Royal bloods with a gigantic monstrous transformation, caught in the middle of political turmoil and discrimination yet are willing to sacrifice themselves in order to save those their love albeit with extremely different methods. Again Eren likely has better opponents).
Clive Vs
Tokinada Tsunayashiro (Upper class men who can utilize the powers of others at the price of their own lifespan yet while one wants to create a better world free from divine interference and full of hope for the future the other has a nihilistic approach and wishes to spread his malice and cruelty across the world while revelling in the despair of others. On top of being niche as AF, Bleach in general is a verse that doesn't really have that many worthwhile MUs for DB).
Clive Vs a Nasuverse character (We all know there will ALWAYS be Nasu equivalent for almost any popular fictional character you can think of however there are better and far more eye-grabbing MUs for Fate to make their inevitable Death Battle debut with).
And that's all I got right now.
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