If you don't think Orks are competitive, and for some reason, don't believe their constant tourney and GT wins, then try playing against a Nob/Nob Biker Army that is built for tourneys. That army rapes faces for practically EVERY army.
Simply put the strategy is this, equip a nob biker unit completely different for every model. That gets you seven to eight bikers I believe. Put a pain boy in the unit, which grants feel no pain and the ability for a 5+ invul. Throw in a war boss. Now the retardation begins.
Because every model is different in the unit, wounds can be spread out so that the combat effectiveness of the unit is still operating at 100% even though they may have taken 8 wounds. Also the minimum strength in the unit is 6, 7 on the charge. They have 4-5 attacks each and a toughness of 5. They also move flat out in one turn, and the next turn can charge. Couple that with the 4+armor (cover), feel no pain, 5+ invul, and it gets real dumb.
Now have two of these squads and two rather large units of nobs equipped VERY similarly in battle waggons and watch what happens. Lastly add in any other unit to fill in points. Oh and ALL of these units are scoring seeing as how they are all troops thanks to the twin warbosses. This army is ridiculously good. You can theory hammer in all day, but play it and you will immediately see what I mean.