That depends on your needs within your family, anonymous. Obviously, you’ll want something that can travel, so I wouldn’t recommend wailord, snorlax, ferrothorn, or the like. Also, it may be advisable to avoid pokémon that are commonly barred from either travel centers or entire regions, such as most noxious poison-types (standard muk, weezing, etc.) or members of the voltorb line. Some regions also bar common spore- or seed-producing pokémon, such as parasect, to avoid the accidental introduction of invasive plant species.
Beyond that, the sky really is the limit for you (forgive the possible pun). Ask your grovyle if it has any preferences, and if not, consider catching local pokémon in the regions you travel to or finding a pokémon you would most like to travel with yourself. The former option is honestly the one I recommend the most. Going out and catching pokémon from regions you visit encourages you to explore each region and befriend a wide variety of pokémon. This in turn will naturally broaden your horizons more than restricting yourself to two partners from a region you know.
Best of luck, and safe travels, anonymous!
The Pokédex According to Bill 