I just caught myself a CATERPIE and a WEEDLE and evolved them both into BUTTERFREE and a BEEDRILL[respectively] to help me. And I suggest your entire team be leveled up to 10, since it won't go any further than that (when I played it)...
ptdgames
At rock cave
Pokemon Tower Defense is 1st generation pokemon only, so no fourth generation or second generation evolutions (including Steelix). Therefore, Onix can't evolve.
beat it with a pokemon that has the advantage
In the cave place. I think it is lvl 3.
you beat the giant onix and show a guy a pikachu lv 42 and a electrod and you will get a shiny voltrob
Nothing.
In Pokémon Tower Defense, you can catch an Onix in the Rock Tunnel area. This location is accessible after progressing through the game, specifically around the Kanto region. You may need to defeat certain trainers and navigate through the tunnel to encounter Onix. Make sure to check for any specific requirements or conditions to increase your chances of catching it.
well the only one i know of is one you can make. onix to steelix
you have to go to the dark cave on chapter 4 and you will have to go left twice.
In Pokemon Yellow Onix does not evolve, it is a one stage Pokemon.
in violet city walk around in the trees towards the nw and you will find the guy who will trade you it