Well, there’s actually a prompt to opt out of the kanji and play it with hiragana/katakana only, so you could always do that. But if you wanted to play through with the kanji @ a 75% recognition rate, I’d take a wild guess at level 25-30. Considering you’re only at level 2, I don’t want to discourage you, but that’s just my guesstimate. You could, of course, go through it the way you did with Harry Potter in Spanish, and use Japanese dictionaries to look things up, that’s up to you.
There’s also this thread: Translating Pokemon Black (Until First Gym) - 100% Done
I’d encourage you to take a look. It’s kind of right along what you’re trying to do.