I have the ougi Water cannon at level 60 (max level) and momotaru's evolution essentials at level 6 (i thinks lvl 6 is max too), but this skill dont evolve

I think Ougi maxes out at Rank VI. I've never heard of anyone with a Rank VII one. I seem to recall another player (maybe Ryxa) saying they'd finally maxed Ougi Crimson Flame Blast Smash VI after a year of grinding, or something. SO it sounds like Rank VI is the max. Until CS decides to up that, if they do. Maybe in the year 10,000.

Skill Evolution 6 can only evolve up to rank 6. Haven't checked the Bow ougi but ougi can only be evolved once.

SeekerFate's Skill Guide may help.

@Helix
Ougi generally level up pretty fast since most people use them often. Especially skills like Rapid Storm and Thunderbeast -Well, as long as you have a decently levelled Momotarou.

Sad... Watter cannon should be able to level up to 7 (because you see 2 bars of water cannon skill when you go to momotaru's skill evolution screen...), but you cant because there is only rank 6 evolution essentials... (I think). In a distant future probably they will add more, since some players have 999 friendships with all partners lvl 30.

Skill evolution currently maxes out at rank 6. (Also yes, I'm the one who took a year to get CFBS to 60 because it's a bad spell and I don't actively use it.) I have heard that JP players have rank 7 evolution but I can't confirm that personally. Either way, I know for a fact that we will never have rank 8 as an evolution because Momotarou will hit max friendship level before he gets it.