Or you bring directly an item to level 8 or you bring some items to level 6, what you absolutely want to avoid are level 5 and 7.

About charms unless you use mb or af blitz teams you want to go for the even levels, so all rank4, then al rank 5 and so on. For the blitz teams instead you want to power up as much as possible mb for the mb version or tenten gnw for nin/atk and mabui for hp/def/res for the af version.