Little Cup and Uber Pokemon are both types of competitive tiers.
The Little Cup tier contains all eligible unevolved Pokemon in the game. Here is a list of Little Cup Pokemon. To be exact, a Little Cup moveset is simply a moveset for a Pokemon in the Little Cup tier.
On the contrary, the Uber tier is one of the highest ranked (if not the highest ranked) tier(s) of the competitive metagame, which even includes legendary Pokemon. Likewise, a list of Uber Pokemon.
I know nothing about competitive tiers, so if you want to know more, I'm not your girl. Lol. x)
Hope I helped. :)