User blog comment:DaigoUKnow/Who is your future buddy?/@comment-11454852-20131217142419/@comment-4292163-20131217195605

^What Tyrant said. Similar to Vanguard, you can retire old monsters to make room for new ones.

Personally, I don't think we have enough cards for me to decide on a buddy. Whatever it is will probably have a retire effect though, retiring the center monster looks like a big deal in this game.