So, I need a little tip on how to beat the Villains Vendetta with all three characters in BBS and it's on the PSP (I have been trying to do so, but gave up since then) alongside with all boosts and commands.
Of course, the newly HD game would be easier. x3
Hmm. I think I can help best with Aqua, but there are some basic stuff you can do with all the characters, to prepare for Villain`s Vendetta.
So start with abilities. I know I have said this earlier, but get at least these four abilities for all of the characters: Second change, once more, heal block(the name is different with each character, but the effect is the same) and leaf bracer. To get heal block, you need to have a block command(LV1) and maxed out Curaga. Meld these and you will get heal block. As the name implies, you will gain HP when you block enemies attacks. Second Change is obtained by melding blizzard and blizzara plus Pulsing Crystal. Once More is obtained by melding Fire and Fira plus Wellspring Crystal. Finally, Leaf Bracer is obtained by melding Aero and Aero plus Pulsing Crystal. With these abilities, you life becomes much easier.
Also you should get abilities that shorten your load time etc... If I remember correctly there is an melding item which description says that it might attach an ability, which shortens your load time. I usually got an magic command time boost, when I melded two magic commands with that item. So this logic can be used with the attack command too(I think).
In Villains Vendetta all of the enemies you encounter are bosses, correct? For Aqua, there is a good strategy, which I discovered a while back. I learnt, that Triple Firaga stuns bosses, making them more easier to beat. If you have more than one triple firaga, you can stun the bosses for quite a while. I think even the last Iron Imprisoner can be stunned, but it is quite hard to hit him. Shotlocks are quite powerful also, and I used Prism Rain. I suggest using long range shotlocks, not the ones were you charge at the enemies. I also think you should use long range attacks on most of the bosses, since they move fast.
Also using commands like thunder surge and fire surge are really useful and powerful, since they are strong attacks, and also give you invincibility frames. You can make them even more stronger, if you gain fire boosts etc.. Again I think there is an item which description says that this might boost your power on certain elemental attack. Meld this with commadn like fire and fira and you get abilities like fire boost.
That is about all that comes to my mind right now. Aquas and Ventu`s mobility also gives them some help, but Terra`s dodge is just terrible. I think I`ll try VV (if I can make that far today) with Ventus and share more info, if I acquire some. Hope these tips will give you some help, all thou I know they are basic knowledge.