Which episode did Ash get his Butterfree back?

Well he had to it was Butterfree mating season if he didint his Butterfree would never have babies or be happy.But he did the right thing and his butterfree is with who he wants to be with.He did the same thing with Pigeot and Lapras but Pigeot had to protect the forest and Lapras was reunited with its mom so it had to go.