I just thought of something... Pirahna Plants Amiibo is coming out in a week, actually it's already being put on shelves in some Walmarts along K. Rool and Ice Climbers.. Sakurai said it takes about a Year to finalize an Amiibo, Ridley, wolf, K. Rool, inkling and Ice Climbers are all out within the 3 months of Ultimates release so we can assume that they were decided and designed early on so they could release in time, I'd even go as far as to say the Amiibo were probably decided upon as the roster was made up in the order characters where decided upon... so doesn't it seem a bit odd that Pirahna Plants Amiibo is out so soon considering he was a DLC character that "wasn't finished".. I personally think this is more evidence that PP was moved to DLC to attempt to prioritize another character.. Rare spirits in the code on the cartridge, there was one cut character slot in the data of the game (probably PP's) according to data miners, I still think there's a chance Banjo may have been attempted for the base game but missed it due to Sakurai getting the rights too late (PapaGenos theory about E3) I think PPs Amiibo is decent evidence that his character was developed much earlier on then we think. It's just strange to me that an incomplete DLC character would have an Amiibo ready to go before characters like Simon, Richter, and Incineroar or even characters like Pokemon Trainer who would have been way earlier in the decision process if idea of bringing back everyone was in the plans from the start.
Look at the gap of how long it took for us to get Amiibo for the DLC last time around..