Chance: 12%
Even though I believe in a lot of points Cosmic77 made in their analysis, I cannot give Mipha a score as high as they did for the simple reason that I think the Champions all have an equal-ish shot. 8% might seem low for Mipha, but it assumes that there is a 30ish% chance of a champion entering the fray, equally divided across the four.
I cannot convincingly pick Mipha over the others, as their differences are all very slight but I do think Mipha has the edge.
Daruk, Goron Champion, is a heavyweight with a weapon unrepresented in Smash yet. He also has the legacy and moves of the Goron tribe under his belt and his shield has shown to be quite versatile.
Unlike the Zora Tribe, the Goron tribe has a consistent design matching Daruk and are more combat ready than Zoras.
Urbosa might seem the most boring one of the four by virtue of her weapon being a sword-and-shield combo.
However, this combo allows Urbosa to pull of a variety of combat moves from Breath of the Wild, as shown in the DLC cutscene, where she shield bashes a Yiga Clan member. Her shield allows her to shield surf and her affinity with electricity is potentionally the most versatile Champion ability of all and could even mesh with her metal sword and shield like some puzzles in Vah Naboris.
Revali is a polar opposite of himself. On one hand, the Rito tribe quest has nothing to offer and his Revali's Gale can be seen as the most obvious, yet boring Up B. On the other hand, the archery aspect got a lot of love in Breath of the Wild and his personality and moveset are quite obvious
Mipha has a lot to offer.
Her Zora tribe is a recurring tribe in the Zelda series.
Her healing power is one of the more versatile and unique ones.
Her spear is a weapon never seen before in Smash
Vah Ruta's ice attacks give Mipha a reason to use Cryonis to further enhance the defensive playstyle
Due to this, I do think Mipha has a slight upper-hand over other Champions, which is why I give her 12%
Want: 50%
Meh.
Lemme try and make a moveset
B: Heal
Side B: Cryonis
Up B: Waterfall Swim
Down B: Mipha's Grace (But its the part where you don't die instead of the heal, aka possible super armor on command)
Even worse than I thought
I'm in the mood, here comes Daruk
B: Boulder Breaker (But it breaks shields)
Side B: Ready to Roll!
Up B: Cannonball
Down B: Daruk's Protection
Playstyle: Keep away, threatening with disjoints, flustered up close. Standard heavyweight stuff, really.
And Revali
B: Bomb Arrow
Side B: Revali's Gust (Aimable curve of wind)
Up B: Revali's Gale
Down B: Revali's Flight
Windbox Boogaloo, featuring highly explosive arrows and regular arrows to pester
Urbosa
B: Parry (The kind of stuff Link does in BoTW. Default is Shield Bash but you can adjust the control stick for stuff like Flurry Rush)
Side B: Shield Surf
Up B: Gerudo Moon (It's Aether, but the thrown-up sword + lightning can give you some cool stuff)
Down B: Urbosa's Fury
Anyway she boring in-game