No wierd rules in the way you mean. As stated already, super discounted economy fares (the lowest ones) don't earn full miles or EQMs in all programs but most "normal" economy fares are OK in all programs. You'd be best off going to one of the websites of the airlines involved and looking at the mileage earning rules. Or checking out the stickies in some of the forums like Flying Blue or Delta (links to The Definitive “How To Earn Delta Air Lines SkyMiles” Thread). Other than the exceptions noted above, all SkyTeam flights earn elite qualifying miles in all programs as far as I know.