Teneban:
Those matches were online wern't they? I can just kinda tell from delayed reactions.
You just need a lot of work on your nanner setups. Grabs are great followups but there is a lot that you can do. Use the second banana for better setups and a free F-smash. You can kill a lot quicker this way. I also think you need to take more risks off stage. Diddy can set up some great gimps if you try hard enough and get used to it.
Dair should be used sparingly on-stage and works specifically for spikes rather than a regular attack. Fair and Bair work a lot better than dair and can be set up with a banana or used to punish an air dodge/spot dodge.
ZSS can be tricky but over-all, naners should stop most approaches. Her long range isn't that difficult to get around and her ground attacks can be easily punished. Keep distance with a backwards glide toss and avoid blindly rushing her. Her naner game is better than most characters but Diddy should always take priority on the ground.
That hacked FD was amazing too. I really need to homebrew my Wii soon.
Count:
I don't really play doubles much so don't take what I say very seriously, I may be just talking out of my *** but I will try.
I realize how difficult it becomes to try to use Diddy well in Doubles and he really isn't a very good character for it. Banana play becomes severely limited most of the time so you really have to focus on his nonana traits. Some of his best assets are his fair and his cartwheel. Fair is a killer move no matter what you are playing so I don't see how it is limited in doubles. Cartwheel for damage, creating space, and versatility.
Don't know what else to say sorryz.
Check out some of ADHD's doubles videos. He has new ones of him and sk92.