It does a bit, since every party will be represented in the European council based on the number of votes they have. It's not an election where the winner takes all.

I think the pirates had one or two representatives in the council, which is enough to start debates and make proposals. They obviously can't push anything through by themselves.

Yes. In most European countries even small parties can get seats. In my country there are 8 parties in parliament, for example, and 2 of them didn't use to be there 2 election cycles ago (they were too small/new 8 years ago but eventually grew in popularity and got enough votes for representation).

Of course if they only have 1 or 2 members in parliament they typcily tend to form coalitions with other like-minded parties so they can get more voting power.