In Friend Safari, all Pokemon are PREDETERMINED (that is, already chosen by the game). So when I say you are a Growlithe, Charmeleon and ? that means when people add you to their FC list they will get those Pokemon in the friend safari under your name. To get the third Pokemon revealed to others you have to do the following:
1) Have Pokemon X and/or Y
2) Beat the E4
3) Be online the same time I am, that is, log on to the player search system in the bottom screen.
There is no way you can change this and in my opinion you have a good set of Pokemon because people can search for a shiny charmeleon and growlithe and get the Pokemon of their dreams.