Hi where do you get the super rod!im having trouble. Can someone tell..

To get deoxys you will either have to cheat using an action replay or gameshark or migrate one over from one of the previous games where you had one using pal park. That of course cannot be done until you have the national dex, which most likely requires beating the elite four. Its not johto it's sinnoh. And to be honest youve got some pretty slim chances, the highest level in the elite four is a level 66 garchomp on the champion, it owned my level 67 empoleon in one hit. I would suggest keep raising them all to at least level 60 and make sure you have super effective moves for everything. Oh and evolve staravia into staraptor obviously.

Train to level 60-70

Um, you're going to have to do some serious leveling before you fight the champion, or even the elite four. Also, get rid of Uxie for Azelf. Deoxys can be obtained via cheating or transferring from previous games.
The super rod can be obtained in the battle zone after the elite four and after you've gotten the National Dex.

First you must get the National Dex to get the Super Rod. It is located at the Battle Area. You need to beat the League as well to go there. The Region is Shinnoh, not Johto. Anyway, your chances are slim. Level them up to at least the High 50s for your best shot. Why isn,t Staravia a Staraptor by now? And I already answered to Obtaining Deoxys, but you also need the National Dex to unlock Pal Park too.

To get the super rod, beat the champion, and complete the sinnoh dex.

...Your odds of winning are zip. Train a lot more.
To get deoxys, beat the champion, and migrate from the GBA games.

High levels arent really needed, just high speed and VERY powerful attacks. I beat the champion's lvl. 63 Lucario with a single close combat from my own lvl 44 Lucario, along with the rest of my mid-40s team.

The elite four all have lvl 53's - lvl 59 so you might need to train a bit more