It was definitely interesting as the metagame constantly changed. Basically, any combination of pokemon worked, whether it was a group of UU, or BL pokemon, or just a random physical tank, special wall,a nd so forth. Unorthodox movesets were also very fun, such as a random reversal/salac set, or running a CB Alakazam with Focus Punch for taking out Blissey. Pretty much, it all boiled down to prediction, and sadly, the game evolved into a heavy tank metagame I even take credit as having, what I believe to be, the longest justified RB battle ever, being 823 turns (give or take) with mirror tank teams The long battles became stressful, but I do take credit in winning that longest battle with a little hax on my side, and against what people regarded one of the greatest players, imperfect luck It is a heavy tank based game, and often gets stalled a lot. That is where you must predict what you opponent will do, as they will switch frequently. Take out one tank of a tank team (against most), and you essentially destroy their team to a specific sweeper. HAX (an amazing amount of luc, such as 6 consecutive rock slide flinches from a dugtrio) is possibly an even bigger impact. It happens a lot and anyone can get pissed at it
It gave Metagross the ability to learn Explosion, Thunderpunch (both groundbreaking moves for him) as well as allowing many other pokemon to gain substitute?
Eh, I guess the first that comes to mind is the whole concept of IVs, EVs, and natures. The funny thing is, GameFreak never actually intended for people to exploit the system they use (it was originally discovered by players through hacks), because the whole point of it was to give the Pokemon more stat diversity in R/S/E and beyond. Of course, they kept using the system the way it is because they wanted to please the competitives, as well as newcomers and vets.