Hello _-EmeraldCat-_,
If you haven't known about this yet, Steelix is a pokemon from gen 2. Only gen 1 pokemons could gain XP and level up in the Kyoto region. Same goes with gen 2 pokemons, they can only gain XP and level up in the gen 2 world, the Johto region. If your Steelix is obtained from an egg then it is possible for it to gain XP in gen 1. Another way for your Steelix to gain XP is by letting it hold an Exp Share. I hope this answered your question if you have any other questions feel free to message me on discord or the forums! Enjoy your adventure on Pokefind
Last edited: Nov 11, 2017