I honestly don't know another way.
You potentially level it up somewhere without saving the game. Beat the Elite 4, but don't fight the champion. It may help if you have a way to reset EVs. Gen VI has a few methods, but any earlier, and you might have to rely on berry lowering IVs (the antivitamins).
You could also level up in a place with a common encounter. For example, you can Surf and beat Tentacool and Tentacruel, and then use Grepa berries until you clear the EVs.
Otherwise, I don't know an easy way to do it, unless there is some person who shows your Pokemon with different stats. I don't think there is one, though.
Tell me what Pokemon it is, and I can show you its range with associated IVs.