>>56430616Something in the "helping" field is good- counseling, therapy, social work- all assuming they go to school for it. They've got healing moves and teleportation to work as medical aids or long-distance transporters. They could also work as fortune tellers and I think a really undervalued one that may have some use is as a Pokemon/Human translator. Psychic types like Gardevoir could beam thoughts into others' heads so they could easily telepathically translate for both parties or even teach both parties how to speak or communicate with one another. However, the last one's niche might be overtaken by the rampant popularity of Rotom Phones/Dex.
All of these are related to a Gardevoir's abilities/moves and implications of species traits through the Pokedex- it's not an exhaustive list and would change based on the individual Gardevoir itself. You might meet a Gardevoir that really likes desk jobs or retail or libraries or idol work or something...