Ok I got the Marvelous save thanks to PCPace.
I noticed the translation is not using hi-res text for the credits, so it's possible the Japanese version will look fine.
So, if someone is willing to test, it seems like a lot but it's real easy, but it might take a few tries because there's a timer to get to the ending, so use save states!Please use the original Japanese version, and use ID 1E11 (Hakchi).
Pick 2nd save.
Press Y to gather the 3 characters together and enter the door above.
Place one character in a switch, use R to pick another character and place each on a switch.
When asked who will stay, select 1st one (Deon).
Press Y to gather characters and exit room.
Once you drop down, press R to leave behind the fat kid and stay with the thin one (he walks faster)
Press switch below, leave room.
Once outside, go all the way down, then left, then up. On the 2nd screen you'll see a hole with some stairs. Use it.
Once inside, take stairs on the right.
Go down, right, up and you'll see the character that stayed behind. Press Y to gather him. Leave this area the same way you came.
Once outside, go down to the next screen, then right, then up to go back inside the temple where you left the fat kid.
Once inside, you'll see to the right two levers on each side. Press R to move the thin and small kid to the right lever, and place the fat kid on the left one.
Press A and once they stop taking, select the second box on the right (Teamwork).
Once they get into position, HOLD A for the thin/small kid to pull the lever, once they do, release A. Repeat until the bar is filled.
Once that's done, press Y to gather the characters and get in the balloon on top.
You'll have to press A rapidly now because some critters are going to be pulling you down. If you don't have at least 13 seconds left by this time, you won't be able to make it out.
Make a video of the credits (not the ending, that one is fine).