In omega Ruby, grimer is in Mt. chimney I’m pretty sure, heracross in the safari in the northwest grass, you need an Acro bike to get back there, abra can be found in granite cave, grovyle has to be your starter of course, Rhydon can also be found in safari, kekleon can be found around the tree fort area on route 121, magnetite can be found somewhere around route 110 and will eventually evolve into magnezone, sandslash can be found in the desert storm area around route 111, and I’ll just figure out how to get lucario buizel and smeargle in Pokémon x and then trade it to my friend and then back to me on omega Ruby, quick balls are probably the easiest way to catch them all but i want them all in regular poke balls so that’s how I’m gonna do it, to get the exact genders I want I might just breed them with dittos if you wanted to do something similar or just know the process I hope this was helpful or at least interesting
Edit: it’s actually much easier to find a magnemite in new mauville