I personally think Ivy's whip is plausible, and relatively useful with its bladed sections and relative length. I however doubt that it can form together to become a solid short sword, meaning that outside a whip's limited range its relatively useless. I think that metal arm fitting has some sort of armor quality and some sort of limited weapon quality with those pointed fingers. As for her outfit, I could easily see how uncomfortable it could be, but its not enough to completely remove movement or ability to use a whip.
C. Viper on the other hand has a lot going for her. her outfit is not impeding at all and allows her to use her ability to be relatively arcobatic. She also has some sort of spy training and all that. Im not quite convinced her gloves can create lightning as large as in the games, but a shock from 1-2 feet is plausible, as is being shocked by a punch. The plausibility of this voltage being in a pair of gloves Im throwing to the future tech clause. Her jet boots Im thinking are her biggest draw (well, not quite biggest lol). They increase jumping height, movement speed, could save her from a deadly fall, and could easily burn her foe from a kick.
As for wondering about if Viper can get close enough to nullify the usefulness of Ivy's whip, I think she can. Her jet boots allow for above-average movement abilites, even more than her natural prowess. She also has stealth training so Ivy might not even notice her until she's in range. I also think there's a chance Viper could catch the whip in her hand and send a shock down the metal parts to Ivy's arm. Overall, Viper has about 800+ of 1000 matches won.
Also, Id like to rant again about the fact that up to this point, 5 competitors have been completely taken the ability to use their weapons because theyre "too big". Kratos, Cloud, Sephiroth, Black Knight, and Nightmare. Nullifying their ability to fight just by saying "lawlz wepun iz 2 big u cnt fite" is bull****, and unless you have a good amount of evidence to back it up, it doesn t make sense. Id like to show everyone how the swords of all 5 of these fighters are plausible IRL. Prepare for large text wall:
KRATOS - Krato's blades are not that large and realistically wouldnt be all that heavy. I could see why the swinging them out on the chains and instantly retracting them thing might be sketchy, but the blades themselves are not implausible as weapons at all. Im befuddled as to why these were considered unusuable.
CLOUD - Easily the most difficult for me to justify, Cloud's sowrd does indeed look implausibly large, but we have the FF7 fans (and the future tech clause) to thank for telling us of hte light training and experimentation done on Cloud, which could easily increase his strength and ability to above human limits.
This is also a testiment to how this could be used by untrained/experimented on people could use this sword. Tiring and moderately difficult? Yes. Implausible? No. Also, as I said, Cloud is above human ability and strength, meaning he could use the sword with relativel greater ease.
SEPHIROTH - This one is also a bit hard t ojustify. The Masamune was like 9 feet long, and was essentially a more japanese-looking Zweihander. However, beyond is huge length, it was a regular sword, quite possibly easier to handle than the Buster Sword. Also keep in mind not only did Sephiroth get as much if not more experimentation on him than Cloud did, and that he was actually very skilled at using the Masamune. Id say Sephiroth could use this quite plausibly.
BLACK KNIGHT - He recieved training from Ike's father, who showed Ike how to use his huge sword plausibly. This alone should be enough, although there is some doubt. BK's large armor might have a burden on him in addition to his Zweihander, but wouldnt he use his training to prepare himself for a combat situation just to compensate for this extra weight? Others said that he has mostly used it one-handed, a way that Zweihanders werent meant to be used. Well, this sword is certainly smaller than the Masamune first of all, meaning it is more plausible for a regular person to use it regularly. Also, BK looks like a very well-built fighter who could possibly use his sword one-handed for a few swings, and has enough training to learn how to use it two-handed.
NIGHTMARE - Nightmare is built the best out of all of thse fighters, and his sword is no larger than maybe 1 foot beyond BK's. He has less options for 2-handed use because of his large armored right hand (which also isnt implausible), but he is more likely to be able to handle it with one hand than the others.
Also, one more thing. Cloud stealing Crono's sword is bull**** and you all know that.