>>55596114I used Magcargo during my first Emerald playthrough. As a Slugma I had to let him be at the daycare for a while until he could at least be an active participant in battle without getting 2HKO'd. Once he learns Flamethrower it's all cool. Also Ancientpower for some omniboost cheese. Sad part is that it takes a long while for it to actually learn Flamethrower which sucks. Maybe spam Smog early on, see if it works?
Just don't give up, it feels very rewarding to have one in the party and make it work.