An egg is my only friend Will that do anything? Do they level or hatch faster if you keep them as a buddy or? ?
When it's leveled up enough, you'll see a green arrow next to the Pokémon in your collection! Click it to evolve~ But, just a tip: if you want to level up something to level 100 for instance, want till you're there to evolve it! Evolved mons usually take more posts to go up a level (that goes for eggs too) (edit: and fossils)