It has officially been confirmed by Ken Balough that Sonic 4: Episode 2 will not be making it to the Wii platform. Sadly, for Wii Sonic fans, this is the third multi-platform Sonic game in a row not making it to their system. It’s seriously doubtful it will make it to 3DS either. I guess Sonic does what Nintendon’t. Here’s what Ken had to say.
But no – the reason Episode I was on the Wii was because we wanted to bring the Sonic 4 saga to the widest possible audience. Episode II unfortunately will not be coming to the Wii – for reasons most people have probably guessed, but that doesn’t mean the SEGA isn’t supporting Nintendo platforms, we have a very strong partnership and will continue to do so.
Source [Sega Forums]