I suppose it depends; there are enough people with similar creatures around here that I've only found it necessary to conceal them if it's something particularly distinctive, or something that you closely and publicly associate with you. I have a few that I can't use on organization business for that reason.

The other time it may become an issue is if the person you're facing knows you, has a Psychic-type on hand, and is willing to use them to read minds, but at that point you have bigger problems than just your Pokémon, I think.

Really, I just raise separate teams; it keeps everything far simpler.