Pokémon, while not necessarily my favourite game, is still one I become routinely obsessed with.
The fact that IVs* exist (yet are, along with EVs**, completely invisible) really makes online battling scene very difficult for a newer player to get into, because even with proper EV training Pokémon with bad IVs won't even be able to get a hit in on perfect mons. This means that either hours (and I mean HOURS) of careful breeding, or outright cheating with an Action Replay are required to get anywhere online. It's a shame because without IVs, it'd be much easier for people to just get in there and let their strategies decide who wins, instead of the numbers.
While some argue that getting rid of IVs will eliminate the need for breeding, there are still egg moves.
*IVs - Individual Values, are hidden stats all Pokémon have that determine how high a pokémon's individual stats can get in one certain area. For instance, at level 100, a Pokémon with 31 IVs (the maximum) in attack will have 20 more stat points than a Pokémon with 11 IVs in attack (assuming EV spread is the same)
*EVs - Effort Values, again a hidden stat, with 255 being the highest in one skill and 510 being the most any pokémon can have, 4 EVs in any area (attack etc) = 1 stat point at level 100. You train EVs by having your mons fight enemies that are strong in the stat you want to train (Magikarp awards 1 speed EV, for example)