Well I can only vote for one option here but I might as well provide reasoning as it's fun to play devil's advocate.
Weavile provides a strong pursuit trapper that can outspeed and ko/trap a large number of threatening offensive mons. It's STAB combo is better than Krook's, it's more powerful than Krook, and it's fast enough to not need to a choice scarf, which makes it harder for setup sweepers to try and take advantage of it. While it does perform worse against Sciz/Rak than Krook, Krook's hardly a competent Sciz check either (takes 75% from +1, LO BP) and Terrak can't take full advantage of you as it's 2hko'd by Icicle Crash (ohko'd by Low Kick) and is therefore forced to click a STAB move to simply kill you, most likely CC so as to not miss and forfeit your balance breaker, which can be played around with the walls of the team. It brings zero defensive utility, sure, but its weaknesses are patched up by the rest of the team, and it is just a far more consistent and more threatening pursuit trapper than Scarf Krook could ever hope to be.
Z-Thunder Latias is the best choice when considering Weavile, as Gigavolt Havoc allows it to better pressure bulky steels, whom also happen to be the primary switch-ins to Weavile rn. Otherwise, just a very solid win-con in general.
Weavile provides a strong pursuit trapper that can outspeed and ko/trap a large number of threatening offensive mons. It's STAB combo is better than Krook's, it's more powerful than Krook, and it's fast enough to not need to a choice scarf, which makes it harder for setup sweepers to try and take advantage of it. While it does perform worse against Sciz/Rak than Krook, Krook's hardly a competent Sciz check either (takes 75% from +1, LO BP) and Terrak can't take full advantage of you as it's 2hko'd by Icicle Crash (ohko'd by Low Kick) and is therefore forced to click a STAB move to simply kill you, most likely CC so as to not miss and forfeit your balance breaker, which can be played around with the walls of the team. It brings zero defensive utility, sure, but its weaknesses are patched up by the rest of the team, and it is just a far more consistent and more threatening pursuit trapper than Scarf Krook could ever hope to be.
Z-Thunder Latias is the best choice when considering Weavile, as Gigavolt Havoc allows it to better pressure bulky steels, whom also happen to be the primary switch-ins to Weavile rn. Otherwise, just a very solid win-con in general.