Champions won't replace Showdown. It will be monetized by GF and if you want to use all of the EV IV training features you will have to do some microtransaction, judging from the trailer. No PC port means missing out on the most profitable gaming fan base. No guarantee that every single mon will be included, else you can just pull out the Tera Eletric Shedinja strat and disrupt the balance of the entire meta.