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I would've taken the culling. Heck, I'd be fine with a dex count of 150 mons in game IF they bothered to make genuine improvements to the presentation.
Scale the world properly, give pokemon more expression and life, akin to stadium/battle revolution, more interaction with the overworld, full on co-op play through the main quest, a non-linear adventure that encourages exploration.
You can trickle pokemon slowly into the game so long as you are attempting to compensate for it.