There's only a few characters that I think really have trouble in tournament..
Yukiko, Labrys, Kanji, Elizabeth
Shadow labrys definitely is not a character that has trouble. Don't know how that character is anything less than terrifying, especially since her defensive options don't suck, unlike her Non-evil counterpart.
The commonality to all of the weak tournament characters is weak defensive choices, can't really fake it in a game that restricts backdash on wakeup and has roll vulnerable til frame 3.
To play these characters, you need to be brilliant with 2B AA and Guard Cancel frequently. Best of luck