So in Mass Effect one you could avoid either Garrus or Wrex if you chose to, are there any party members you can avoid in ME2?

Not sure because I didn't do this in my playthroughs, but I think Legion and Grunt can be avoid being recruited.  You can just leave Grunt in the tank and Legion inactivated, right?

You can just give Legion to Cerberus, too.

Zaeed for sure you can leave un-recruited.

I didn't recruit some other people not mentioned here on my second playthrough.

I think you can leave Grunt and Legion alone and donate to cerberus.

i think a couple of them can be skipped. i think you can enter the relay and skip any unrecruted members after that but i think you have to complete a certain number of story quests before it triggers. from what i can tell tho i dont think the IFF will activate until you at least completed all of the recruiting mission regardless if they joined you or or didnt somehow. i believe that legion can stay deactivated or be sent to Cerberus labs. and you will loose him. and i think that you can leave grunt in his tank. but im not sure. i believe that you cant skip jacob or miranda as they are given to you from the start. and as hat king said samara can be killed during her loyalty  mission but is immediately replaced by another asari biotic.

you can leave grunt in the tank the whole game if you want.

You can skip Zaeed, for obvious reasons. You can leave Grunt in the tank and sell (give to Cerebus) Legion for a stack of credits.