I have a bravery that is holding a cell battery witch takes care of the supereffective electric type attacks and all that is left is rock if you could help me that thanks. :)
cell battery doesn't prevent electric type attacks. You still receive damage, except your stats get boosted.
And as of I know, there is no ability or item that Braviary can get to prevent rock type attacks.
No there is not, at least not in the real Pokemon games. On Pokemon showdown however there is a CAP Pokemon with a ability to not consider rock type moves when it first comes into the battle.
no, but you can always teach him superpower, which is super effective against rock types