Early game, right when Frustration is starting to get weak, you get Return. The early game (when you have Azurill) is essentially all Tackle spam where high attack and normal STAB give you a sizable advantage. Most things aren't 1HKO's, and speed stats are terrible, so Lillipup/Azurill are essentially pushes. Azurill easily pulled its weight early game, lagged a bit when it evolved and lost the STAB, then just started wrecking stuff when it learned Aqua Tail.
I'm only midgame in my playthrough, but lower high/upper mid tier easily.