In the resent chapters of D.Gray-Man we have seen all the generals in action. General Marian Cross beat Tyki Mikk's transformed state without any trouble...it even seem like he was toying with Tyki. As for the rest of the generals...we saw them fight a large number of akuma. They destroyed them like nothing...which leads me to my question why don't the generals kill of the noah clan it doesn't seem like they would have any trouble against them...and as for the Millennium Earl i'm pretty sure Cross can defeat him.
Haha, don't bring up Yeegar...he was a disgrace to the generals.
Yeegar was old - and taking on two Noahs at the same time certainly isn't an easy feat (emphasis - Yeegar was OLD).
Also, the Generals kicked ass with level three akumas - when the surviving four teamed up -together-. The Noahs still are strong as all Hell. And remember, the level three powered up to a Level Four and now we're unsure as to their fate, in particular Tiedoll's.
I think they instigated that Cross couldn't take down the Earl alone - group effort with all of them, perhaps. But also, if you wipe out all the villains at the beginning, then there's no story.
I wouldn't say that Allen would officially count as a General, as he hasn't had promotion, but as a Critical, his power could be considered that as he's at 100% - though certainly some of the other Generals have surpassed that. Sokaro has his one form, powerful as it is, and Cloud Nine seems to have two forms with Lau Jimin, and hint that the whip may have something to do with another as well.