Guide for Defeating Final Boss - Guide for Mario & Luigi: Superstar Saga

When the battle starts, Bowletta will appear. I reccomend starting with Thunder 
Bros. to lower her defense, then nothing but Bros. Moves from then on. Note: do 
not use any items at this stage of the battle unless you really need to. If she 
spits out fireballs, jump to dodge those (I reccomend pressing A and B at the 
same time) then ignore those and just attack her with Bros. Moves. She could 
cause blocks to appear above your heads. Jump five times each to destroy them, 
then jump to dodge the flame she shoots at you. If she turns black, stars will 
start raining out of the sky. Purple stars don't hit you, Mario will hammer red 
stars to knock them back at Bowletta and Luigi will hammer green stars. Soon, 
she will look as if she is defeated, but at that moment, a time Bob-omb will 
step out and explode. Note: this does not reflect your actual time, but simply 
comes out when you've given her enough damage. Bowletta will then proceed to 
swallow Mario and Luigi.

In her stomach, your HP is automatically set to 1 each, so have Luigi use a 
healing item. Max Nuts or Ultra Nuts work best. Cackletta's ghost is there, and 
she has three main body parts: her hands, her head, and her heart. Her heart 
will only be exposed when you defeat her hands and head. After the heart is 
exposed, it will pump to revive the body parts, but for the few turns that is 
is available to attack, unleash everything you've got on it. To kill 
Cackletta's ghost, damage the heart. She has many attacks.

Heart: Most valuable part. Can heal hands and head.

Hands:

Right Hand--Unleashes a ball of electricity on you, hammer it back and forth 
between Mario and Luigi and it will disappear. Note: The more damage you give 
Cackletta's ghost, the longer it takes for this to disappear. The right hand is 
vulnerable to fire and electricity will heal it.

Left Hand--I myself find this harder to dodge than the right hand, so I take 
the left hand out first. The left hand causes snakes of fire to swirl around 
Mario and Luigi's feet. You must jump at the same time to dodge it. It could 
change directions at any time, so stay alert. Note: Like the first hand, this 
takes longer to disappear when you've damaged her heart enough. The left hand 
is vulnerable to electricity and fire will heal it.

You will know which hand is attacking because it will stick up one finger just 
before the attack begins.

Both Hands--The basic 2-hand attack is that the hands will come up to you. 
Hammer them to deflect them. Later on, they could change places, so the one you 
thought was going to Mario could suddenly move to Luigi. A more advanced 2-hand 
attack is Cackletta's ghost swings her hands around. Look at them carefully 
because some you have to jump over and for some you shouldn't jump. As you 
attack Cackletta's ghost's heart, the length of this attack grows.

Head: The head has many attacks. I will list them from easiest to dodge to 
hardest to dodge. Note: At any time, the head can heal itself or boost the 
power of any part of its body.

Attack 1: A glowing orb will come down on Mario or Luigi. Hit it with your 
hammer 4 times to bounce it up and down and eventually break it.

Attack 2: The ghost of Fawful will appear. It will launch a straight line of 
glowing green orbs across the brothers. If the mouth grins, the line will start 
at Mario, and if the mouth spins around, it will start with Luigi. Shortly 
after this, Fawful will approach one of the brothers and laugh. Hit it with 
your hammer to get rid of it.

Attack 3: Many glowing orbs are produced in random positions. Most of them are 
blue, but some of them are red or green, in which case it will disappear and 
reappear a little bit away from the corresponding brother. Time your hammer 
shot to deflect it at Cackletta's ghost. Note: There will be a lot appearing, 
so keep your eyes peeled and reflexes sharp!

Attack 4: Cackletta's ghost's head will freeze time and shoot lasers at both 
Mario and Luigi. Some you will have to jump over, and some you won't. To find 
out, look into her eyes. They will point where she is aiming. The eyes closest 
to each of the brothers correspond with the matching ones. If her eye is 
looking down, jump. If it is looking up, don't jump. Note: This seems simple 
enough but the real challenge is figuring out when to jump so you are suspended 
in midair at the time she freezes time.

To defeat Cackletta's ghost, just survive her attacks and use a lot of Bros. 
Moves. I find that a hand can usually be defeated using a Bros. Move and a Solo 
Jump. The head needs about 4 to 6 Bros. Moves.

In terms of what Bros. Moves to use, I like to use Chopper Bros. with Mario and 
Knockback Bros. with Luigi, but you should just do whatever you're most 
comfortable with. I find Fire Bros. slightly less effective than other Bros. 
Moves like Splash Bros., Swing Bros. (Secret, obtained in cave where you get 
the Super Hammers), and Chopper Bros. Luigi's Bros. Moves are all good, except 
don't use Thunder Bros too much because it doesn't lower Cackletta's ghost's 
defense and the head and right hand will only get healed by it.

That's about all I can tell you for help with the final boss. Good luck!