Here are skills would characters the best can have
Goku: king kai fist 20x super saiyan(1 2 and 3)warp kamehameha super spirit bomb
Kamehameha(or only potara)
Picollo:destructive wave, sync with nail, fuse with kami, light grenade, hellzone grenade, special beam cannon
Gohan(adult):kamehameha, jackhammer, super kamehameha, super saiyan, super saiyan 2, elder kai's unlock ability
Vegeta:galick cannon, final flash, meteor flash, meteor break, super saiyan,
Super saiyan 2
Great saiyaman:justice punch, justice kick, justice carnaval, justice flash

Super Buu is the best buu if you unlock absorption to get absorption you need 10000 kili and then you unlock it what it does is, is when you use the move super buu picks a random person and absorbs them and takes on two of there moves so if he happens to absorb gotenks he gets victory cannon and super ghost kamiakaze attack, another example is vegeta lets you use galick gun and final flash, cell is energy field and spirit bomb those are the only characters I have seen him absorb so far

When the match start dash to the person you are fighting and hit the punch button
To knock them on the ground then when they get up start to punch and keep punching until their energy on orange then use kamahamahamaha or a move lke
To finish them off

Use the heart desiese and vacination to kill your opponent faster

The best character (in my view) is a customised Vegeta to look like this:-
Super Saiyan, Super Saiyan Two, Galick Gun, Big Bang Attack, Big Bang Attack, Angel's Halo, Meditation.
Fully powered up this Vegeta's Big Bang Attack can cause nearly two bars or seventeen hundred attack points when successful. With the Halo he won't loose Ki from powering up and the Meditation means he only uses have his Ki per attack so he remains really powered up throughout a fight and opponents will be left on th flat of their backs.

Go to Babidi's ship in the main menu press A. When you get in there go to 1player. Then go to stage 4 use a turbo controller turn the turbo on B and you should get a boat load of killi..!

It's not a cheat but it's very helpful choso (spelling) Gohan as ally then where Goku bring Goku and Gohan at the same spot and when you battle Gohan wil have Max Ki.

To get more money buy all the Sparklings in the skill shop.

Once you buy all the Sparklings!!! equip them to anybody of your choice.

Once you do that play in the world tournament and you should get a little bit more than you got.