TMNT Vs. Teen Titans
 

Which universe do you think would win in a fight?

Leonardo Vs. Robin
Raphael Vs. Starfire
Mikey Vs. Beast Boy
Don Vs. Cyborg
Splinter Vs. Raven
Shredder Vs. Slade
Foot ninjas vs ??? (whatever Slade's soldiers are called)

Rob Van Dam

Superfly Jimmy Snuka

Leo and Robin would be pretty equel
Starfire would annoy Raph to death or just distract him with her nudity
Mikey IS Beast Boy... only without the shapeshifting
Don vs Cyborg... well they could compare robot parts if it was Cyborg Don from Image
Shredder and Slade would become best friends and then Slade would bore Shredder with tales of all his kids....
Splinter would teach Raven other ways to control her emotions...

Well the toon Titans would be handled pretty easily, but in the comics it'd be much more interesting. In that case, the TMNT would have to hope that Superboy had detention and Kid Flash was busy on XBox Live or something.

Big fan of the Titans comics; the show, not so much. Any version of the TMNT would wreck the Toon Titans.