Any GAM songs. Hell, the whole GAM album could've been the W album.
Many speculated that Viyuden's Issai Gassai Anata ni Ageru was a recycled W song, and a few said the same about a MM song.
^ None of Koharu's solo songs are written by Tsunku.
I have this vague memory of reading from somewhere that it was supposed to be another ye olde jpop cover album.Well, can't remember for the death of me where I saw that.