I don't believe anyone in the UCL to be bad at Pokemon, simply because none of them are. They're all there for a reason and that reason is because they are PokeTubers with wide (and overlapping) audiences that are strong competitive players. No one should be shamed for how they do in battle as, well, it's a video game and also as a result of the immense being in a league battle where their reputation as a pokemon battler is on the line. I didn't really understand it before this current Reborn event/league (RCBA), but now that I'm getting into it more, I see exactly what people like Shady are freaking out about and people like Nappy are letting decisions come down to the wire because the pressure is just crazy. Not to make this about me (because it definitely isn't. it's just a personal example), but going into each battle before I took a loss this RCBA season I kept thinking: "Is this is? Is this where my streak of victory ends?" and it finally did with Sparky by me playing absolutely abysmally and by Sparky simply making his best possible plays. As Joey always says, you don't need to make a cool, flashy play all the time, but rather save that for when you need to catch up and make a play to win. Simply make your best possible play most every turn and you should do fine.
I don't believe any of the UCL members to be bad- not Shady, not Kristen, not David, nor any of the other 13 coaches. They may not always make their best plays and they sometimes forget themselves, but they're all good people and good battlers who deserve to be recognized as such. Sure, Kristen may not be doing so hot right now, but she may just be the David needed to take down Joey the Goliath.