I head into the next room, where, according to a note, I'm supposed to speak the password into the horn based on the hints I have to open the door forward.
Here are the five hints I found:
--Two of the letters are vowels
--Four are consonants
--One has an S
--Two letters are side-by-side consonants
--It's something from the sea
Whenever I'm below a block here, a prompt appears with a selected "key letter", and five other letters.
By jumping on the block, I move the cursor letter right to the next one.
By the fourth hint, I'm guessing this word is plural.
The first key letter set has these letters (I'm putting the set here if in any case the screencap above doesn't load or something happens to imgur): m c o t p
Second set: o t e s y
Third set: a r e t s
Fourth set: a t r s c
Fifth set: t e r l o
Sixth set: s t e k r
Now what combination could I make from these letters?
From reading the list a few times, I'm guessing "pearls" since they could be retrieved from the sea.
I have Mario speak the password into the horn. I'm right!
The door opens...
..and the giant squid's, or the giant Blooper's, tentacle comes out of the horn! No battle yet, thank goodness!
I save at this point before facing the giant squid in the door!
I wonder which tentacle should I take care of first?
After Bowser gets out the right tentacle, one of the remaining tentacles throws Mallow out of the battle!
After a turn, and removing another tentacle, Mallow comes back!
The third tentacle then takes Mario for a high-flying ride!
There goes the first set!
Unfortunately, the second set is a bit stubborn, as one of them takes Bowser for a midair cruise!
Lucky the tentacles are vulnerable to fire!
After Bowser's trip, Mario's next again!
Now the real battle begins, against King Calamari, the Giant Blooper, and his two tentacles!
Mallow's scan reveals his thoughts: "The ship's MINE! SCRAM!"
King Calamari also has a few tricks other than an Ink Blast: a Sand Storm!
Now he's taking turns attacking the whole party and taking Mallow out of the battle!
And he has a Drain Beam too!?
After a few uses of Mario's Super Flame, King Calamari is no more!
Now it's the tentacles left!
The tentacles have a mind of their own too! One tentacle's mind reads: "You wouldn't EAT me?!" *shudders a bit*
After more Super Flames, the giant squid is finally finished!
After the battle, we fall into the chasm where the giant squid used to be!
I use the bouncepad to jump back up to the password room, go back to the save room, and I stop here!
Oh my god, this was a very long session to play through!