This all you need to know.
It's a tier in competetive battling in which the Pokemon are level 5, cannot be fully evolved, and have to be the first in an evolution chain. The Pokemon can only know egg moves and cannot know moves that it learns at a level past level 5. Some pokemon are banned from little cup, such as scyther, murkrow, yanma, sneasel, tangela, misdreveus, and meditite. The moves dragon rage and sonic boom are also banned. The deepseatooth is banned, because it can give clampearl up to 36 special attack. Event moves are also banned.Generally it is uesd to test the power of level 5 pokemon.And yeah it is in game
Hope this helped!