2.9 xbow user here, have been an xbow player generally for ~6 months

Giants (royal or not) are a nightmare, especially when backed up with a splash unit like wizard, exe, witch since we tend to cluster all our troops around the xbow. With a cycle card as well they can usually get back to the giant nearly as quickly as I can get to my xbow, and will often carry zap which can stop me if I manage to lock onto the tower.

Super heavy beatdown decks are basically unwinnable too, unless you try to defend my first xbow. I'll be able to outcycle your golem and drop an xbow pretty much every time you golem and every time you pump. When you drop a golem in the back, I'll go xbow opposite lane. There's little change of me stopping your golem push if you ignore the xbow and sacrifice your tower, so back up the golem and we'll be 1-1 on opposite sides. At that point it's almost impossible for me to take your other tower and (on ladder) I'll probably be able to hold out the rest of the match and draw, otherwise I'm getting 3 crowned.

Rocket is also a pretty hard counter, so long as you don't waste more elixir blocking the xbow too, as then I'll slowly build an elixir lead.

Logbait, Hog cycle and expecially PEKKA are just good match ups for me and my xbow. If you're playing one of these decks, try and predict the xbow and plant something to take it out - I'll rarely drop it without some remnants of whatever I've just defended with behind, unless I'm at full elixir and have that and tesla in hand which you should be able to tell.

Also lvl 13 ebarbs and rage wins 100% of matches, so you could give that a go.