diddy dittos are easy, stay stationary, minimum glide tossing unless you have control of the nanerz. you just can't be pressured, and don't up b every time the other diddy has a banana, theres a chance the other diddy will know and just let you charge em away for nothing. I love the ditto its my favorite matchup. You just need spacing, that's totally it. Spacing is the key to winning, spacing throws, naner placement, everything. naner-less skills shine in this matchup also because there are times when you have to go head on against your opponent without nanerz. Oh yeah, don't forget the pluck edgeguard, diddy sucks against his own edgeguarding skills :D as the nanerz falling down deploy his barrels and screw up his side b so you can edgehog him. Just practice is all and you will kill other diddys who dont know how to play against their own character. if you're opponent diddy has control of the bananas, then try and space yourself away so you can pick it up on the grond with a (NOT A DASH ATTACK), if you dash attack like crazy you'll just trip everywhere and be punished.
Can we go over ice climbers? It's a fun matchup, but can be very bad as well. Diddy dittos don't need alot of in-depth discussion, can we do two at a time? Ice climbers that know how to handle the nanerz can be pretty nasty, they even have a glide toss.