The mutual attachment simply does not compare to the Pokemon you've had with you since the first few routes/cities. The final factor for me is if the Pokemon has a good movepool and/or a fun little gimmick that doesn't suck. Stats don't really matter as much as long as they're ...
or Zubat had a deeper cry and it took 69’s cry instead when it was deleted. It seems like GF had a hard time making this guy, looking like a Halloween decoration over here. It may have had … only a mouth?