When Level Ball is out, Weavile might work better.
Until then, I'm going to change my mind and agree with Celebi23– Weavile isn't needed, because in most cases the only time you'll get it up is when your opponent has already knocked something out, which defeats its own purpose. I'd say the four spots could go toward something else.
Now what I'm worried about is just running 4 Durant and a Rotom, and maybe a Mime Jr– that will lead to a lot of mulligans. Is anyone else worried about the opponent starting to attack T2? Because that could definitely be a huge problem, if you're giving them so many cards to work with. And starting with Mime Jr could mean Tyrogue donk (which is why I wouldn't play it if I didn't, though it's still a possibility).
How about Pichu in this deck? I'm leaning away from it myself (just get Durant with Collector/Dual Ball and skip setting up your opponent), but I feel like in starts where you have a Dual Ball and no other search for Durant, one could at least get the Pichu.
EDIT: How are these lists not tight on space? I was having trouble finding space for Eviolite, even... with Catcher, wouldn't you want an Eviolite on every Durant to save from being OHKO'd? I guess ideally you'll be discarding some Catcher, but that won't stop your Yanmega/Donphan+PP/etc from getting Catchers out.