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252+ Atk Choice Band Tera Bug Lokix First Impression vs. 0 HP / 4 Def Zigzagoon: 542-638 (249.7 - 294%) -- guaranteed OHKO
I hope this calc makes you happy.
Fun fact: In generation 4 of pokemon, in the pal park, shuckle is found on the ocean tile set which means it can swim. With a base speed of 5 though, it can't swim very fast.