Zimbob Invaderpants is the greatest crossover I never knew I needed. Thank you. My life is complete.
All of the Angelica ones are pretty bad but the cross with Mr. Krabs takes the cake.
I'm not going to talk about the Krumm crosses. Those are all their own levels of Hell.
I don't remember TMNT ever being on Nickelodeon. What I remember was them being on during after school cartoons on the regular antenna stations, and sometimes in the mornings during the summer. I think they had a Saturday morning run for a bit too.