>>25023625It isn't, it's more of a time thing. Suppose you don't want Geodude on your team in the long-run. You're spending a solid hour of your time, then, at the very start of the game grinding it up (which is hard because most trainers are in Bellsprout Tower and have Bellsprouts) to a level high enough that it can survive Pidgeotto's mud-slap. After that, you're probably going to ditch it once you kill Bugsy's Scyther.
>>25023658In most games this is true -- RBY is the perfect example of this, actually, where there's literally nothing early game to take out Brock if you chose Charmander.
GSC's levels suck though. There're only 13 trainers to fight before Falkner. Half of these are in Sprout Tower, so it's still dull/not fun to level Chikorita up because it takes so long to kill Bellsprout. GSC's levels are shit the whole way through. It's also easy to get stuck at your rival in Azalea because you simply don't reach a high enough level with your mons battling trainers.