We all know and love Pokemon (that's why we're here), and the entire premise of Pokemon is, arguably, battling. Differences in power, moves, and items result in some Pokemon being obviously "stronger" than others (Axew and Mega-Rayquaza, etc.). But some Pokemon need actual other Pokemon to be near them to reach the amount of power that others have. Here are a few of those Pokemon:
Slowbro
The obvious one. Both the anime and games reference the thing on it's tail as a Shellder, and the result of a Shellder biting Slowbro's tail is pretty amazing. Massive stat raises, a new look to Shellder, and new moves. Some of the moves I can't understand how Shellder caused Slowbro to learn, but whatever. It's interesting to note that in Slowbro's mega, Shellder has almost fully "consumed" Slowbro, but he appears to be fine with it. Maybe it's armor, or maybe Slowbro is just a little... slow.
Exeggcute
This one is a bit weird, seeing as someone might think that the Exeggcute are just one creature, and are just being moved mentally by one of the Exeggcute, but according to Pokedex entries Exeggcute are definitely multiple creatures. Their evolution, Exeggutor, is only one creature, so I would assume they formed together. Nevertheless, fighting an Exeggcute isn't absurdly difficult, so imagine fighting just one of the eggs. (Maybe the one with the cracked head?)
Binacle
Not much to be said about this one, just that they are definitely two different creatures.
Barbaracle
Pretty much the same as Binacle, except now there are seven Binacle. The Pokedex entry states that the Binacle "multiply", as opposed to finding more Binacle. (Also, even though it says they fight with the power of seven Binacle, if we cut Binacle's stats in half, and then multiply by seven, we do not get Barbaracle's stats.
Kangaskhan
In it's non-mega form, I wouldn't say Kangaskhan "needs" it's baby. Maybe emotionally, but I cannot imagine how that baby helps Mama Kang. However, without an adult Kangaskhan around, the baby is completely helpless. And when Kangaskhan mega-evolves, we may be able to assume that the bonus stats the Pokemon gets come from the baby, meaning that Mega Baby Kangaskhan has a base stat total of 100, which is believable.
Well, there you go: Those are a few of the Pokemon that actually require friendship.
-Prescottio, Tamer of Shuckles