I would've answered with the contents of that page myself, but I was worried that it was outdated. Also, this answer is actually missing some Pokemon. The complete list from Bulbapedia (if it's up-to-date that is) is:
Baby (the Pokemon that ride in your arms): Pichu, Cleffa, Togepi, Smoochum, Elekid, Magby
Shoulder (the Pokemon that sit on your shoulder): Caterpie, Weedle, Pidgey, Spearow, Pikachu (after it collects 10 Pikachu Candy), Eevee, Natu, Sunkern, Murkrow, Wurmple, Plusle, Minun
I clicked sort ascending/descending by position to easily find the Pokemon so I didn't have to go through the whole list.