If you really want, and I remember most of it. Also it may be a little like the other idea proposed, but I only skim read it so I'm not sure how alike they are.
First of all, the key component was the Biju mounts, which I have included on the test server. In order to get the Jinchuriki 'KG' if you wish to call it that, you would have to reach the reset level of kills, and have one of the Biju as your mount. Then you would reset as the Jinchuriki of that Biju.
Now of course the Biju would be of different strengths, ie Gobi < Kyuubi, but there would be other advantages to picking a lower Biju, such as the lower Biju not being as rare or hard to get, and also you can master the full power easier.
Now each reset you would master two tails, or one of the last if you're an uneven tail number. Each tail beast would start with a basic few moves, ie Sunaton for Ichibi, Yoton for Yonbi, etc. You instantly get the Biju's buff constantly all gameday as well, in addition to any other mount, though you can't have another Biju as your mount.
After a kills, you can use the tails you've mastered, V1 form, where you get the bubbly chakra cloak for a buff. Once you get to 30+ or so kills, you get the V2 forms of though tails as well. After 50+ you can use a Biju bomb in V2, the power determined by how many tails you are currently at.
Once you master the tails, you get one last reset, which allows you to follow transform into the Biju, and use the full power Biju bomb too.
Example reset patter, using Gobi.
-Reset 1: Obtain basic jutsu, constant Gobi mount buff. Obtain V1 and V2 forms for tails 1 and 2.
-Reset 2: V1 and V2 for tails 3 and 4.
-Reset 3: V1 and V2 for tail 5.
-Reset 4: Complete transformation.
We were thinking of other requirements, like no other KGs to get this, or sacrificing a fully completed one to start this, maybe a higher DK limit to reset as well.
