Lafleur has a good case even by my definition, because Orr got hurt and that gave Lafleur an opening to be a top guy for a very short period. But that era is still Orr's to me. It got taken away from him early but it was still his and Lafleur was keeping the seat warm for Gretzky.
Beliveau was no Howe and later on I think Hull was the top guy between Howe and Orr.
Ovechkin has been a PPG guy for the last half a decade, he lost his generational cred with me a while ago.
But deciding on what "generational" actually means is like voting for the Hart, so you're not wrong to consider them to be that. For me they don't make it.
So many posters including myself have tried to break down players based on tiers.
I think you have the Big 4 with Howe, Gretzky, Lemieux and Orr being the obvious choices and in a tier all on their own but the next tier is a list of players who are indeed generational;
Morenz, Richard, Plante, Beliveau, Harvey, Lindsay, Hull, Esposito, Lafleur, Dryden, Bossy, Bourque, Leetch, Chelios, Roy, Hasek, Jagr, Lidstrom.
The 3rd tier you've got Mikita, Shore, Sawchuk, Parent, Clarke, Park, Robinson, Dionne, Trottier, Potvin, Messier, Yzerman, Coffey, Stevens, Belfour, Fedorov, Brett Hull, Oates, Francis, Sakic, Forsberg, Selanne, MacInnis, Brodeur, Ovechkin, Malkin and Crosby fell in this tier although near the top of this tier.
I think in hindsight all 3 (Ovechkin, Malkin and Crosby) will be remembered as generational but being generational doesn't mean it's exclusive to one player per generation either.