Pikachu isn't the only Pokemon who can jump unto your shoulder in Pokemon Go. Obviously, they should be small enough to fit on the shoulder area; you wouldn't do that to a Lapras or a Snorlax, you'd end up crushing that avatar. Niantic does its best when it comes to keeping players in the game by promising to release app update every other week or so.
As you may or may not already have known, Pikachu has this Easter Egg in Pokemon Go when chosen as a Buddy. The Pokemon accompanies the player's avatar by standing beside him but to everyone's surprise, it jumps unto the avatar's shoulder after walking ten kilometers. The easter egg may let you think that this is possible to other small Pokemon, and guess what, you're right! However, most, if not all of these Pokemon do not do the stunt pulled by Pikachu. They just sit on your shoulder right away when selected. Otakukart.com has hunted five more Pokemon for us and we sprinkled some fun facts.
Caterpie - Pokemaxx says Caterpie possesses an antennae that releases a horrific stench when frightened. Suction cups on its feet help it crawl on vertical surfaces, it can also sting. This Pokemon is found in common areas and usually in forests, woods, meadows, and trees. Its highest stats are Speed and HP.
Weedle : can be used to grind
Pidgey : grinding a player's level
Spearow - This Pokemon can fly quickly and has the mirror ability to reflect enemy attacks back at them. These Pokemon spawn on common areas but not as often as a Weedle or Pidgey. Speed is also its highest stat.
Here is a video on all Pokemon discovered so far in Pokemon Go that would jump on your avatar's shoulder:
