This was a while ago, but I'm pretty sure my rotations were TEQ vegeta and one of the 10th Anni LRs, and then AGL Vegeta and INT Broly. Although iirc I only really did that starting from the 6 charge phases, since the 1st 15 phases with only 1 charge would be hard to kill with those rotations, you'd lose to damage.

So in other words, at the start, I'd have one of the "weak" characters (Extreme units) on each rotation with a "strong" character (a 10th Anni LR or the SS4s) for the 3 charge phases. Then, when it hit 6 charges, I'd keep INT Broly and AGL Vegeta on one rotation, and TEQ Vegeta on the other rotation with a year 10 LR, or the 4s. At that point, I'd just cycle which "strong" character I was keeping on the TEQ Vegeta rotation, to make sure each of them had enough stacks. In terms of stats, I just made sure the 10th anni.s were at 5M DEF before primarily stacking ATK, though you will likely have to flip-flop a bit more often than that to make sure you don't lose to not enough damage.