I really wish people would stop complaining about how Magcargo(and other past entries) suck,and instead post something constructive.
Because at the end of the day,it just means that the OU pokes get all the attention and get healthy entries,but everything below is left in the darkness.
So you call Magcargo bad?Prove it in another way bar stating "its typing is bad". That typing allows it to maul major fire types such as Talonflame,Volcarona,fairy types and ice types without 4* SE coverage (which you can predict since the opponent wouldn't switch it in otherwise).Ferrothorn,Skarmory and Forretress can't do much to it,whilst Magcargo incinerates them in return.
Magcargo@lum berry/leftovers
Flame Body
-Recover
-Ancient Power
-Lava plume
-Stockpile
Spatk. focus(~150),then split what's left over into bulk. You switch in and try to burn something with flamebody,opponent switches out whilst you lava plume / recover.You know that opponent has just sent something in with an appropriate counter move,so you switch yourself.Late game,stockpile becomes very useful.Or,if you need to specialise,acid armour or amnesia - it gets both.The secondary effects of both attacks are very useful too.
Other things I have tried:
-Inferno & Will-o-wisp - the latter because it's reliable,but the former is also useful because your opponent could be switching that turn(meaning the turn before you switch you could deal a hunk of damage AND burn the "counter" switching in for free).Both have advantages,both are useful for weakening the opposing team.
-Infestation also works well,especially if you've burnt or toxic poisoned the opponent already.
-Toxic is also useful for whittling down things that have recovery and/or sp.def boosting moves.Volcarona is also less troublesome.
-Yawn is alright - but the other statuses are more threatening.
-Shell smash - it really isn't that worthwhile,because neither offense is that spectacular,and its base 30 speed is bad.On top of this,you're sacrificing your defences - the more valuable stats.Fun when it does work though - exchange with stockpile on above set,and use weak armour instead of flame body
Counters?Sure,it has counters.Loads of them.Water,ground,fighting,rock.But Magcargo doesn't care.If it can burn some opponents for the team,and the team in return can cover said counters and take advantage of its support,does it really matter?No, it does not.The crucial thing to remember is that it's a supporter and not a sweeper.