Are battles determined by level or trophies? Just curious.
Matchmaking is based entirely on your Trophies.
Your level, Townhall level, and experience does not matter.
As of the 2015-04-30 "Air Sweeper" update, matchmaking does not depend entirely on your trophies. Aside from your trophies…
You are now more likely to find targets at or near your Town Hall level in multiplayer matchmaking.
Players with an equal amount of trophies, but of different Town Hall levels will see significant differences in villages they are matched with.
As of the March 2016 update:
Town Hall 10 and 11 players are less likely to find each other in Multiplayer. Now that more players have progressed to Town Hall 11, we can make adjustments to matchmaking that will result in less TH11/10 matchups. Note that players in Champion league and above will not be affected.