If i'm playing on the Old Pkmn Games and i'm catching a wild Pidgey at lvl.2, what is the best strategy to level him up as the same level as your Starter Pkmn?
Grind against other Pokemon. Things like Chansey and Audino are veritable gold mines of EXP, and quite a few other Pokemon yield decent amounts as well. Fighting Trainers gives even more, plus you get some money out of it.
Dump your Pokemon into the Daycare. This takes a while, but prior to Gen 7, Pokemon in the Daycare gained 1 EXP for every step you took.
Exp. Share. If the Pokemon you want to level up is too weak, have a stronger Pokemon come in, and the EXP. Share will level up the holder.
Rare Candies, when applied to a Pokemon, boost said Pokemon's level by one. This is not recommended for lower-levelled Pokemon.
I can give specific strategies per game if you specify what game you're playing.
Hope I helped!
