Longest winning streak: Asuka ~231 matches, 914 days

Win/loss records matter, no matter how much WWE tries to skirt around the fact. We'll start with the most notable win/loss record of all.
Asuka went for a span of around 231 matches and 914 days without suffering a pinfall or submission loss, a streak that lasted from her arrival in NXT in October of 2015 to WrestleMania 34 in April of 2018.
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The closest active competitor is Ronda Rousey who is at about 24 matches (according to profightdb) and less than 365 days into her own streak. To beat Asuka's record, Rousey would need to continue as is into late 2020 in time and for hundreds of more matches in length. Neither scenario seems likely to occur.
No other superstar seems like a probable bet to even match Rousey's current streak, let alone the one that Asuka amassed up until last year's WrestleMania. This one is going to stand the test of time.
Asuka has been an integral part of the growing diva's division in the WWE and is one of its top competitors.