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I honestly have no idea. Just give me the best possible Miltank that you can think of (without egg moves) in a Love Ball. Something that could play well in 4th gen UU as well as 5th gen RU/NU.
I guess Jolly Thick Fat lets me run the most sets, right? Since it can turn offensive if need be!
But I can get more sets out of Jolly or Impish I think because there are speedy support options or tank pivots and what not. I just can't imagine Careful without Curse. Lemme know which one you choose. I need to think of a nickname. I was going to go with Milty after Whitney's Miltank, but maybe something else...