What nature should Bronzor be? and what should the IV look like? I have an Adamant Bronzor but its attack IV is only 9... Is this Bronzor decent for beginner competetive?

If you are trying to have fun and figure things out at your own pace, I would recommend trying out things that you think work and seeing what happens. This is a good way to figure out what you like and what you want to try with your pokemon.

 

If you want to seriously get involved into PvP, there is a competitive website called smogon that has lists of sets (moves, ev training, nature, ability) for each pokemon. This is the link to Bronzong: https://www.smogon.com/dex/xy/pokemon/bronzong/

 

If you are new to PVP, I recommend reading the description for the pokemon you want to use. The descriptions explain why you use certain moves, and why you use the nature you do. While PRO is not exactly similar to the regular pokemon games, many (most) of the sets that are listed there are what you will find in competitive games here.

 

edit: There is also a large PVP section on the forum here, in the Player Zone subforum. Try looking through topics there, as well as some of the guides on team building.