about the game mechanics: they definitely improved; rby was extremely glitchy.
But that is the charm of RBY, and also something you need to deal with.
Also GSC does something the advance generation can't: it promotes a battle to a chess match. In advance, there are so many Pokemon you need to be able to counter that if you forget one and your opponent happens to have that Pokemon it's a 6-0 sweep. Also due to the EV system (which DOES suck IMO) battles become much quicker. In GSC, battles last longer.
The advantage of GSC is that it can really teach you how to think strategically and how to exploit an opponents weakness or mistake. Two teams in GSC that are decently built up cannot ever beat each other unless either player is a humongous lot better than the other, or either player haxes.
remember there are three factors in Pokemon:
1) team: the construction of your team is important. No major weaknesses, no type weaks. That sort of thing. If this is done well (with proper teams, it usually is), in GSC, the teams will be very close and it could very well be a match played at the sharpest of the edge (dutch expression)
2) skill: The ability to predict and to think ahead is very important, and insight to what counters what, what damages what, type resists, and if the difference in this is too large, the most skilled will win.
3) luck: Ever had your team beaten by a lucky critical hit? Ever been paraslammed at critical moments? Blame luck. There is some luck in game mechanics, and some matches you have more than others. Some get more luck than others in some matches (you can ask Trax).
Now, in decent GSC battles, the first two are usually at about an equal level.
The third is variable. Which means that in nearly every GSC match, luck will decide who wins.
This also explains why GSC is a stallish metagame: well-built teams cannot break through each others defensive barriers. In GSC you need just that little bit of luck and surprise.
