Yep!
1. Refers to how he always chooses whatever starter has type advantage over yours.
2. Is referring to Yellow version where he chooses Eevee as his starter, and by definition can't have Type Advantage (at best, he'll get Jolteon which doesn't really have the advantage in terms of typing.)
3. His Grandfather is Professor Oak, which is to say, this is self explanatory.
4. In Gold/Silver/Crystal, he's the Viridian Gym Leader, and his gym is filled with what looks like legos.
If you're curious, my other hints were going to be something like this:
5. My favorite color? That'd have to be blue. - Refers to how one of his alt names is "Blue" in any form he has a default name "Gary" and what his name technically is in Gold/Silver/Crystal (and yes, if someone said "Blue" as the answer, I'd have accepted it.)
6. If you can't figure it out by now, well, Smell ya later! - If you've played any of the first Gen games, this one should be obvious <_<
