The common5 does have a max filesize. To reduce the size, you can re-import the textures as CMPR format.(If they're imported already, just export them and import them as CMPR)
I actually did make it work by changing all the portraits to CMPR which cut the file size drasticaly! so now all I got to figure out it is how to add more costumes to Bowser and Peach. I know for Peach you need a fit.pac or something of that nature but I can't find what I need and Bowser I have no clue why it wont load his last 3 like I said I assume it has something to do with giga bowser.
Are you running 3.5 or 3.02?
I'm using 3.5