Cartoon Network outright owns Bakugan and Transformers Animated is an in-studio show. Pokemon is on there because, seriously, it's POKEMON. CN seems to be fine with airing it, and even if they weren't, Nintendo will pay them anything to keep it on.
Robotboy, now that it has finished all of it's episodes, really has no purpose on DAS other than time filler (though, it may also help that it has a weekday run).