Datacron level 6 relic requirements

Datacron lvl 6 asks for R4, not R6 btw.....

And you can get the lvl9 datacron bonus if the character that has that bonus is R6 and rest of the team isn't. For example: You can have a R6 Hera and the other Phoenix characters at R4 and you gonna have both the lvl6 and lvl9 datacron bonus, you just gonna miss out on the lvl7 and lvl8 stat bonuses.

If you want all the stats then yeah, you need a full R6 team.