>>26644636OU is enjoyable , but you're bound to find a lot of "tryhard" smogoners that may make it a little dull if you're not wanting to make a really smogon cut team and just want to have fun for a little while. You can use almost any pokemon you want, but I do hope the ones you want to use are viable.
UU is a better in that regard, as it's a bit more flexible than OU I think, unless all the ones you wanted to use are banned from this tier. Lower ladders are fun as well, though in there is more of a "see what's available and try to make something out of it" thing, since you get less choices the lower you go.
