Everything Unlocked
First of all, you need the following to be able to perform this exploit.

-A fully Rooted Android phone/tablet

-File Manager capable of accessing the root files (ex. Root Explorer )

-Internet Connection on the phone. Either 3G or WiFi is fine. (to connect to Com2Us Versus Server)

-Version 1.4.0 of Homerun Battle 3D on Android (other versions will not work)
If you have all these things, here is what you do.
Step 1 - First of all, using your Root Explorer, backup your jesus.dat file located on the root files on your phone at (root of phone)/data/data/com.com2 us.HB3D/ Simplly copy it and paste it somewhere easy to remember on your SD card, just in case you decide to restore your saved game back to the original, all you’ll have to do is paste the original jesus.dat file back into that folder.

Step 2 – Go into your game and use all of your Gold Balls to purchase anything that you don’t have yet.

Step 3 – Log on to the Matchup Server and log into any Channel. (with Version 1.4.0, this step saves your items that you have onto Com2Us servers). While you are in the channel, Save at least 20 Rivals onto your rival list, this gives you an extra 500 Gold balls each time you reset (as explained later). Shut down the game.

Step 4 – Now that all your items are saved on Com2Us’s server, use your Root Explorer to Delete your jesus.dat file located at (Root of Phone)/data/com.com2us.HB 3D/jesus.dat

Step 5 – Go back into your Homerun Battle 3D game, just go through the tutorials like you did when you first installed the game. When you are on the home screen of the video game, Press on “Rank” and let it connect to the server, this step is very important, because it loads your Nickname and some of your Stats which gives you Achievement rewards on the next step.

Step 6 – Press Play, and Log onto the Matchup Server and Log into any Channel. Once it loads, you will receive some Gold Balls ranging from 1000-3000+ depending on your previous Achievements and Online matchup Records. Which is why you should have atleast 20 rivals saved, it gives you the Celebrity Achievement. This step also unlocks all of your gears that you’ve previously owned. Log off of the Server.

Step 7 – With the Gold Balls that you’ve just received, go buy any equipment that you don’t have. It’s okay if you still have gold balls left over. After you’ve used up the Gold Balls on your new equipment, once again, Log onto the Matchup Server and Log into any Channel, again, this saves your gear onto Com2Us’s Server. Exit the game and repeat Steps 4-7 until you have everything!

NOTE: You may not have enough to buy the more expensive items, depending on your previous Achievements, but all you'll have to do is get some easy Achievements done and you'll have enough. Remember to log into a Matchup Channel to save your items. If you are starting out fresh, with no Achievements, you'll have to play the game a little bit and receive a few Achievements before you be able to do this. Best Achievements to get are the ones that you receive through Online Matchups, because these are mainly the ones that are saved onto Com2Us's Servers.

This comes in handy too if you want to change your Nickname at no cost to you.

I haven't tried this cheat in a few months, so I'm sorry if they've already fixed it, and if you're successful, please confirm it with a post.

Spread this tutorial around like a virus and please give me credit.
Post Questions or Comments, thanks.

–Nine1Sickness