1) Firstly, that's assuming that Repliku is there to begin with and doing
anything. We have no solid evidence that Repliku is in the Realm of Sleep and those suggesting it is Data!Riku are at least bringing up the idea that he could be inserted into the Realm of Sleep somehow since the ones putting Riku and Sora in the Realm of Sleep have the journal in their possession can throw him in there.
Secondly, the idea of attaining the suit to suppress the ill affects of the darkness were brought up in CoM, where Repliku first made his debut. Having been created by the organization if he needed a suit to survive I think he would have been given one. That either suggests he doesn't need one or he didn't have time to receive one (as far as the story goes because outside of story we can just say Nomura didn't think that far). Either or, putting a suit on him just to link him to the Riku seen in the trailer is where the 'stretch' is.
2)Hmmmm...instead of using the Riku incarnate that I've created recently in Re:Coded (which KH3D has already been said to link BBS, Coded, and Days btw) that's already wearing the attire, has useful information, and has been used as a plot device before and recently...I'm gonna go with the replica incarnate who...fought to attain his own existence. I'm not Nomura but I'm just thinking rationally.
3) Lol... Paint this scenario for me... Repliku is wandering the 'Dream-Monstro' and bumps into his original...makes more sense...than Data!Riku seeking Riku out and finding him in 'Dream-Monstro'? You're telling me he strolled through the dream whale and just happened to run into Riku, yes?
4)...Haha...really? I'm not just pointing at the coat...I'm pointing at a KH1 Riku...wearing the coat... If it was a black haired girl wearing a coat than yes...I'd say Xion. But its a KH1-Riku wearing a coat. And since only two Riku's have done this already canonically and one of them is wearing new duds...I'm going with the other one who wore the coat...canonically.
5) If ya think Repliku has plot relevance for his appearance on the evidence we have than kudos to you. I tip my imaginary gentleman's hate to you sir.
6) I don't see how me assuming they can send Data!Riku into RoS makes any less sense than you assuming that Repliku would suddenly have plot relevance.
7) *sigh*...I can't... Hypothetically speaking if Data!Riku is in there possession and may have information the real Riku might need or hell, that Sora might need, Data!Riku can be of help, no?
8) Yes. A key difference. Walk with me on this one. If I were to place trailer Riku in front of you and placed a picture of Data!Riku and Repliku in front of you, who would you say was in the trailer if you hadn't played either game? (which means you wouldn't assume someone was magically given a coat)
9) which brings me to my lovely gif at the top
10) well...blinding does tend to do that.