okay so I'm trying to think of this kid's cartoon from maybe the 90's? I'm not sure when it was made, I just vaguely remember watching it and loving it.

it was about some dog maybe, or something weird, and his name began with a Z I think, and in the theme song beginning thing he takes a sort of roller coaster down through some tunnel and comes out as a superhero or something like that, but I just can't remember!

I know this is all very vague and it doesn't make things too clear, but it's all I can remember.

"Underdog," maybe?

Spoken by Underdog: "There's no need to fear, Underdog is here!"

When criminals in this world appear,
And break the laws that they should fear,
And frighten all who see or hear,
The cry goes up both far and near for. Underdog, (4X)

Speed of lightning, roar of thunder,
Fighting all who rob or plunder. Underdog, Underdog.

When in this world the headlines read
Of those who's hearts are filled with greed
And rob and steal from those who need.
To right this wrong with blinding speed goes. Underdog, (4X)

Speed of lightning, roar of thunder,
Fighting all who rob or plunder. Underdog, Underdog

There's a picture of him at this link: http://www.cfhf.net/lyrics/images/underdog1.jpg