Dragon Ball Z Budokai HD Collection

I'm not going to lie at all, I was tremendously helped by dL KryZi's solution, but it was missing a few things...

My Capsule Set-up on Goku
Viral Heart Disease
Kahehameha
Senzu Bean

As he mentioned, you do have to beat each tournament and then you purchase them in the Item Shop which can be found by going to the Edit Skills menu. It was always in the Recommended skill for me. To get Zennie you have to win World Tournaments, which you should have one a few by now to get to this Advanced champion achievement.

I used his method which was to equip the Viral Heart Disease, but I did not have Vaccine, and have yet to found it either, instead I equipped a skill or two that takes 1 slot that I usually use (in my case, Goku and his Kahehameha), and a Senzu Bean, all which you obtain through story mode.

*** Thanks to One Eyed Magnus for verifying that you do get the Senzu Bean through story mode!

I set the time to 45 seconds, because without Vaccine, I found myself losing with only 30 seconds, the 45 gave me a better window with the Senzu Bean. The Viral Heart Disease will reduce opponent all the way down to Half of One Bar of health. I would try my best to beat opponent using a combination of melee attacks and equipped skill. Keep an eye on your timer, what I would do is let my opponent defeat me at 10ish or so seconds. Thanks to Senzu Bean, I'd regen all my health, and try to deplete the rest of the enemies health which I would either succeed in, or time would run out and I would have greater health anyways.

**Very important - what you make sure you don't want to happen is get a Ring Out by getting knocked out the arena. I ALWAYS made sure that I would hit Up/Down and A button (Guard) to sidestep and stay in the center of the ring.

With the above mentioned, I lost Advanced only once and got it on my second try.

Doing this should get you all the achievements (if you fully completed Story Mode). Except for the Legend of Hercule achievement, which I got by purchasing it in the skill shop under Recommended.

Negative feedback? Please leave a comment so that I can write better/more simple solutions in the future.

Thank you and good luck!

Basically the same as the others apart from one difference...
Edit your skills for Kid Gohan
Choose a Vaccine! (Needed) this can be got eventually by entering the store and leaving till it shows it sells for 4000 zenie in the recommended section
you also need to use viral heart disease.. and maybe Senzu bean,
Set the timer to 30 second rounds in the options menu.
Start the tournament and pick Kid Gohan "Custom" and start the match,
Try to get knocked down straight away then when you get knocked down hold down and guard till the time is up.. easy as pie. This means you stay on the floor..
They can barely hit you and you don't have to do anything.
Just sit and wait for time to run out and you have won as the viral heart disease takes their health down but you have the vaccine. Senzu Bean is for emergency only just in case but not required

My strategy was essentially the same as "HaZiiHaLo" addition to "dL KryZi" strategy. With the acception of focusing on ringing out my opponent.

How I would go about this was, use my (X),(X),(X),(X),(B) combo and hopefully knock them down. Then stand above their body and as soon as you see them getting up use your (X)+(Y) unblockable attack to send them flying. Then dash towards them by double clicking forward and use the unblockable attack(X)+(Y), as soon as you see them getting up once again, to send them flying off the arena, resulting in a ring out victory. Then if this failed, cause sometimes the AI will counter your unblockable with an unblockable in return, I would resort to the guide "HaZiiHaLo" and "dL KryZi" posted.

hope this helps you guys!