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I've been playing a number of the pokemon games with modded starters as well as beating the game with only a singular pokemon (sans HM slaves). Sometimes the experience goes over well, some planning is required once I decide on who I am to use. The hardest challenge in any gen will always be taking a Magikarp or ditto for a starter. Not only do both of them have extremely limited move sets, they have poor stats and ditto's gimmick doesn't isn't very useful overall.