Here's a more detailed explanation:

Open up the location of the file in Windows Explorer. Windows Explorer is the thing that looks like this: https://upload.wikimedia.org/wikipedia/en/c/c0/Windows_Explorer_XP.png

Use Dolphin to extract the original file that you're replacing and put it in the same location to compare.(Obviously, temporarily rename it so that they don't overwrite each other.) Click the spoiler for more info on how to do this.

Download this and follow this tutorial(Where it documents how to use Clean Rip; the rest of the tutorial you don't need to know for these next steps, as they're unrelated; with the exception of downloading Dolphin; you should download Dolphin to be able to do one of these steps)

Put the .iso file in a directory where you know where to go for your Dolphin games.(You need to browse for the folder and set it as like the default games folder) Open Dolphin and right-click the name of the game that's in the list that you're getting the file from; Click "Properties". In the right tab, navigate to the file you need to get and right-click and click "Extract" on it.

Now, right-click each one and select "Properties" for each. It should look something like this: http://www.nicholasoverstreet.com/wp-content/uploads/2010/03/timestampgood.jpg

And, where it says "Size: ", you want to compare those two numbers. If the replacement one has a larger number, that means that you need to lower its filesize, by doing something like making the textures smaller(less resolution; must be in powers of 2) or removing polygons and/or vertices from the model.

Um...About Dolphin, it is not support my Window 7 because I don't have powerful video card.  I did tried before and mostly I got lagging.  Right now I am downloading SSBB as wbfs and I will use Wii Backup Manager change to ISO, but I won't stay long because I am going work today and tomorrow.   So I might able to finish download on Wednesday because I have day off on Wednesday.

Um... what? I didn't say anything about an internet browser or the disc or any of that. All I said was, the likely cause of freezing is filesize.

No.  Sorry.  I didn't have a chance to check the size file before format my system for recovery.   Guess I have to download ISO again, am I?

What's the filesize of the original file(Extract it to see), and what's the filesize of the new file. It's a 98% chance or so that this is the problem.

Well...I kinda bad news for you.  My computer system got screwed up and can't be fix to use Firefox or other kind of browser.  So I format my computer system.   If that is true for 98% chance will be error problem in game, then I am guessing I have to get real disc and use Riivolution.   I did use it before but I don't have real disc with me.    I will buy it someday.

I need your help with Zelda model for Shantae.   I did change the model and give a try on my Wii.   Game is fine when I load it.   When I finish pick Zelda as Shantae and random character, I press start button as Ready For Fight, but it froze.   I didn't trim ISO or scrub ISO.   Did I do something wrong?

I think you mean "psa", not "pca", and do you mean Wii Scrubber?

Oops.  My bad.  Yeah. I think so that can change PSA and other stuff.   I downloaded and it is what I am looking for.   Thank you.   I am going give a try to change Zelda mod for Shantae that I found it on DA (deviantart) that he made Shantae even she didn't win the vote in SSB4.

Edit: Dang it.  It froze when I press ready to fight and I didn't scrub or trim.   I need help.

I do know how to use put pca and other thing to ISO for SSBB USA version for long time ago but problem is I can't remember the name of utilities on my computer.