Y'know this talk of Piranha Plant had me looking back at his reveal in the Direct and during it I realized just how sneaky Sakurai's wording was to obtain him.
In the Direct Sakurai cleverly uses wording that implies that PP's a pre-order bonus without ever saying it outright:
"something you get if you buy Super Smash Bros Ultimate game NOW"
"Remember Piranha Plant is a free limited time offer"
"We hope you consider pre-ordering it" (as it seaways to an explanation on how to pre-order)
In reality though anyone can get PP as long as you register before
February 1st without pre-ordering.
Maybe I'm just late to the party and everyone already knew this but it was quite the revelation for me on how they cleverly promoted more pre-sales which
apparently worked out in the end.