>>56023547>Make up your mind.I think you should learn to read and use your brain. How much more am I supposed to explain myself to you and avoid simply repeating myself.
Adding in new Pokémon takes more time and effort the more Pokémon they add. Because they are new. Not the case for pre-existing Pokémon. Because for them they don't have to start from scratch.
They reuse and rework stuff from previous games a lot. The have been reusing the textures, models, animations and data for Pokémon and making changes to some of them over time. They don't need to to go through and do a bunch of work for every previously-existing Pokémon, just what they need to do and anything else they feel like. Like how some Pokémon get model updates but not all. Some Pokémon have mechanics changed like Greninja's Battle Bond Ability and Deerling's and Sawsbuck's Forms and some have Base Stat changes. But they also make changes to the code that automatically effect every Pokémon and have them be compatible with the code of the new game and for most Pokémon that's enough.
All of that should be obvious, especially after what else has been said by others in this thread. But apparently not obvious to you. If you still don't get it I doubt I'll reply to you further.