Tabby vs Sheperd: Personally I can see either side winning this match, especially since there is not exactly a surplus of posts to work with, but my vote goes to Sheperd. From what is shown, he can deal with most, if not all attacks thrown his way and retaliate. I don't know anything about either character, but I think the biotic abilities of Sheperd will be able to get him to victory. My vote goes to Sheperd.
Kirby vs Terrarian: Like, I think literally everyone else, I was surprised by how much of a Swiss Army Knife the Terrarian was. Whilst it is very impressive and versatile, I think that Kirby might be able to beat him given his copy ability. We've seen Kirby inhale a weapon of the Terrarian, granting him the Sword ability and lowering the number of weapons the Terrarian has. The Warp Star has proven to be an useful asset to have, providing flight and mobility that can be generated at a moment's notice and it allows Kirby to get the Star Rod, a way to keep distance from the Terrarian and to destroy the traps. We've seen Kirby attempt it with a giant star, a smaller star should be able to destroy them. As for the Terrarians minions, as cool as they are, Kirby ate like half of them before they could truly damage him, main example being the Stardust Dragon. My vote goes to Kirby, though the Terrarian has proven me very wrong on their skill set. Should he be out, he certainly made a lasting impression.
Genji vs Johnny Cage: My vote goes towards Genji. A lot of moves thrown by both sides were blocked or dodged, but Genji has the range advantage. Shuriken are not the most lethal weapons in the world, I think even in game they are not too strong, but a spammable range attack is never a bad thing to have. With the Swift Slash, that smoke screen move and the wall climb ability that has not been used yet, Genji is more mobile than Johnny Cage and can keep his distance. Having explosions on his side, reliable mobility, spammable projectiles and not one, but two blades with him, I can see Genji winning this match
Olberic vs M.Bison: Eliminating all bias from this fight since it includes my own character, I can see this match going both ways. Whilst Bison has been a major offensive presence the entire match, he is canonically one of the slowest characters in the game and heavily relies on Bison Warp to get around whilst Olberic has Spearhead to charge ahead. Olberic also has a way to stay healthy and use his skills more than once, the former Bison lacks and he restrains his usage of his Psycho Power to keep his body from flat out corroding, even though he still packs a serious punch. Olberic is tankier than Bison, but he doesn't have the same instant mobility options as Bison does and is pretty lacking in the ranged department, only having Brand's Thunder to my knowledge which takes a while to be available to be used. It is a close match, and Olberic is in better physical shape than Bison, but I think Bison can pull through if his arrogance takes a backseat and his Ultimate Psycho Crusher hits. Should it fail though, Olberic has an easy time absolutely destroying the damaged and recovering Bison. Olberic is stronger in close range, not to mention he can easily defend himself against the moves of Bison that do not use Psycho Power. My vote goes to Bison, although it is very close.