>>37207801>Is there an incentive for me to battle them and level them up versus rare candiesNo. Rare Candy is perfectly okay to use in gens 1 and 2. Your Pokemon won't end up weaker for it.
>do they get better stats if I evolve them fasterThey don't grow more or faster, if that's what you mean. Only time you may want to delay evolution is with evolutionary stones.
Crystal or not, you need the other Kanto starters and the other fossil.
