Even if you know their team's pokemon, you don't know what their strategies and personality are; you don't know if they're a conservative player, making only the moves necessary to keep their team from being swept, or if they're a gutsy, confident player who constantly keeps the pressure on their opponent. Until you know their team's sets (which could still contain surprises) and their style of play, you can't try to predict their moves and expect to get much success. Although I personally dislike this change, if it has to occur, it won't change the game too much. Even in D/P, it was difficult to find hard counters for every set a sweeper could run; Lucario would often use Agility to KO the Gliscor that would otherwise put a full stop to the Swords Dance set, and Gyarados could easily use a Choice Band and Payback to OHKO the Rotom forme switching in, which would otherwise, again, put a full stop to many almost all other sets. The addition of this change, if truly the only way to play online, would not even decrease early-game conservative play to a substantial degree; although you know the team, you don't know the sets, and they could still wreck your team with an unexpected danger, i.e. Agility Lucario or CB Gyarados as mentioned above. This ability to form a possible plan against your enemy is even more negligible when considering a full stall team: although they utilize prediction, it could hardly be argued that they rely upon good prediction as much as a bulky offensive team, and most of their concern is dealing as much damage to the team as possible, through entry hazards and harmful status. If teams have the right support for their lead, as they should have in D/P, then even attempting to counter your opponent's lead won't work, as they will be able to buffer against the pokemon that threaten it. Seeing your opponent's team, although an unwelcome change, will not affect the battle as much as posters have said it will. Mostly what this change will require is people backing up their weaknesses better and having a team that can handle problems to their strategy, not just putting five random sweepers and a random lead on a team. In conclusion, although I personally don't like this change, as Kitten Bukkake has said, teams will simply need more flexibility to succeed.