I'm glad someone else also noticed that the merch corresponds to the actual events in the series.
I hope we get at least a glimpse of Joker in the next episode because it feels like there needs to be some plot advancement that would lead into the last two episodes, which seem like they will be quite lore heavy, judging by their titles. And since Joker is teased in the intro, I have a feeling that him appearing in at least one episode of the series goes without a question.
If he doesn't appear in the series at all I'll be a bit dissapointed.
So far we saw events from all the sticker merch clones except for Waru with ghost (predicts the 7th episode), Felix with camera (I assume also the 7th or 8th episode, if it wasn't in the 6th), and Fedor (if he hasn't appeared in the 6th episode like this - which I didn't watch yet - otherwise, I assume finale).
However I do want to add that series poster also seems to have some spoilers for the episodes! Notice how, in it, Gabriel is wearing the outfit his mafia game version wore in episode 5.
The thing is, Dante is also wearing some unusual clothes in the poster... Well, at least unusual for the cartoon series universe - his card clothes! I theorise this might be a spoiler for one of the last two episodes, where more fantastical elements like magic could finnaly appear, along with Joker.
As for why Joker is associated with Waru, I'm not shure why this could be, all I can think of is that this connection seems to date all the way back to the meme Green glasses where Waru is depicted making a deal with Joker.
Who knows, maybe this connection is a teaser for some events in the Land of kings comics as well...
These are just my thougths and predictions based on the afformentioned merch.
Btw, I used Google translate to read the original post, so I hope I didn't misunderstand original questions and assumptions.
