By completing day missions(Sonic the Hedgehog missions).
Chat with our AI personalities
Probably not. There are four achievements for collecting half the moon medals, half the sun medals, all of the moon medals and all of the sun medals, so they probably expect you to make an effort with searching for them all.
Homebrew channel. (Hacking)
no. also about saving the world
There are no Rank 7 night levels, so you only need roughly half of th Medals in the game (80 Moon, 120 Sun)
Well.. on the map, there is a place that should say "new"(located on the top middle part of the map (if you know what I mean). It's the place that you can collect sun and moon medals. If you want to reach Tails, then enter the moon door (where it's night and Sonicl turns into a werhog), and finish the misson. After, you will there meet Tails and explore two new more places. Hope this helped!