The Simpsons Game Strategy Guide for the Wii 28: Bargain Bin, Part 2
As for Bart, he does not need to go up the spiral slide, but can use his grapple shortly before getting there. Near the edge of the platform is a crate that Bart needs to destroy which contains the Third Krusty Koupon.
Homer needs to become Helium Homer again to float up and to the left, where a platform with a trampoline awaits below him. The Third Duff Cap will be there waiting.
Bart needs to go over to the area across from this Duff Cap, and use his Grappler. He will then obtain the Fourth Krusty Koupon.
Both of these characters need to take the trampoline up to another trampoline, where they will find the ramp they need to be on. Bart needs to run to the end of the ramp and use his grappling hook. As for Homer, he needs to become a Homer Ball and launch off the end.
There are some Dual Pressure Pads here that both Homer and Bart need to stand on. Once the door opens, all that is required now is that one of the characters run down the ramp and pull a lever.
The level will end here. You will then get to a point where you need to find four KeyCards.
At this point, you are learning some upgrades for your powers, and the characters you are working are Homer and Lisa. The first thing you need to do is get your upgrades from Frink.
When Homer goes to see Frink, he will flick out a Green Gem. Have Homer use that Gem, and he will be a Gummi Homer after he eats a Gummi de Milo. Have him use his Gummi Grenades and his Jello Pound on the football player foes that just show up for no apparent reason except for demonstration purposes.
Lisa needs to get her upgrades, which can also be done by talking to Professor Frink again. You will then need to grab a gem, go see the Buddha statue, and thus perform the lightning ability. You will then encounter Video Game Cliché 17: Lame Tutorials. Signs will show up saying that Marge and Bart will get upgrades too.
There is another cliché that needs to be found here. Go up the stairs on either side, and head to the door that requires the aforementioned four keycards, and you will encounter Video Game Cliché 18: Key Card.
From there, you should find another cliché. Go down to the five movie theater entrances below, and take the one in the middle. You will then be transported to the house. There isn’t much to do here but check out the collectables in the characters respective rooms. You should also get back to the theater through the laptop in the living room, which will bring up Video Game Cliché 19: Rift Portal.