Ian takes on countless forms, so complete documentation of them will be impossible, but some have been converted into playable Mii Fighters in Super Smash Bros. for Nintendo 3DS and Super Smash Bros. for Wii U as a way of viewing their characteristics and powers in simpler ways for humans to understand.
The Fighters Edit
Listed below are screenshots taken of the Mii Fighters of Ian's forms that currently appear in the game. All screenshots are currently from Super Smash Bros. for Wii U. Including his base form and excluding variations brought on by custom effects and Master Ian, there are at least 81 known and documented playable Mii Fighters of Ian's forms.