Whoa, there's alot of bad info flying around here.
On gaining weight, everyone can do it. The simple reason why people who are stick thin never can is because their metabolism is so friggin fast no amount of calories they throw at their body is an excess. People such as this, which sounds like Shorties bf, usually have no other option but to turn to weight gainers which are absolutely loaded with calories specifically designed for such a purpose.
Protein shakes are meant to supplement an already solid diet which has a good macro breakdown. To induce hypertrophy you need a good balance of protein, carbs and EFAs. If any of those are missing it just won't happen.Who said 'other supplements' are bad for you? Endless studies have been done on Creatine, Glutamine, etc, and have proven that if taken properly they won't cause a problem. Perhaps your bf forgot to take in alot of water with his Creatine?
If you have all three parts of the weight gaining equation in place- Smart nutrition, smart training, and quality rest, you will make gains.