If you had to axe 3 of the most popular species from ME:A...

Ever heard of Saren and Warden Kuril? The latter was the main antagonist in Jack's recruitment mission and the former was only the best villain in the entire Mass Effect series.

I know, right, and to a productive, allied and completely law abiding Citadel member state no less? As if that wasn't enough, they did everything they could to spitefully piss on their ancestors for 3 centuries as well, all the way up to endorsing slavery and ethnic cleansing.

Oh not the rats....you mean the other intelligent species they were too busy ignoring in their ivory tower? Right, the frogs. Guess they all deserved to starve. Dummies shoulda uplifted a galactic scourge of battletoads or something to save themselves like a real species.

Still, Council could've done worse. Either could have ended up like the rachni.

I'd axe all the non human Council species. Better yet, kill off the asari (they're a quick breeding plague like the rachni, who are at least nice enough to only take dump planets noone wants). Kill 99.5% of the turians and force the rest to live in deep space, enslaving them if they come into yours. Then, put krogan on the salarian homeworld (seems only fair, it's their fault), watch the former eat everything and then force the latter into a dumb compact where they have to do boring science and mathshit for everyone else that we can't be bothered with. Seems only fair.

Oh, and when the next big galactic menace comes, I want an air quoting amnesiac quarian, a comically racist krogan and a conniving, secret hoarding volus to first deny it exists, then pointlessly obstruct the people trying to fight it, only to deny it some more before finally deciding to do absolutely nothing about it.

My money is on Drell, Geth and Salarians - none of them were able to be on your squad in ME3 (even during the Citadel DLC).  If they continue that trend, they're gone.

And not taking everyone is unbelievably impractical from a writing standpoint.