Leveling Up The Characters

Earlier today, I played Kingdom Hearts Birth By Sleep, and I worked on leveling up the characters. When I finished their stories, they were all at a medium level, not too low and not too high. I worked on leveling up all 3 of them because I wanted to get all 3 of them ready for the secret bosses. Fighting these bosses will be my first attempt with all 3 characters, but I've seen how people have beat them on YouTube and I will follow some of those strategies. I won't keep spamming Tornado during the Vanitas' Sentiment battle though, that will seem boring, I will use other commands like Sonic Blade, Strike Raid, and Mine Square. I will definitely have to be careful because one hit by Vanitas' Sentiment can get you in critical health; the second chance and once more abilities will be hugely helpful in both battles. I also remember that I can't use the Curaga spell when fighting Vanitas' Sentiment because he will also cure himself if you use it, but I know that you have to use normal items to cure yourself. I will post another update in a few days to let you all know how I did.