Very well thought addition for waterbending to make someway realistic ,as i do support this. I think the amout of bottles you wod need tk have would depend the abilities you will want to preforme ,as it will have a limit by the amount of water you contain in bottles .Like for surge if you have only 2 bottles(all filded), then by doing the wall or wave thingy ,the size of it would be 2 blocks high and 1 block width ,but if you have 5 or more bottles ,then the size of would be equal to the ordinary surge. If you would contain only 1 ,then you wouldn't be able to perform it. In torrent cases ,you would need to atleast have 2 or 3 bottles to torrent. You can spin it around yourself and shoot it like normal ,but you won't have the skill to release the giantic wave as you won't have the proper amout of water to do so ofc. You would need to have atleast 24 bottles in order to do so. PlantBending would have the same thing. If you select a source with surge or torrent ,then it will work if the plant contais more blocks then 1 (cactus, leafs (on the tree), sugar cane, vines, ect.)