Focused teams are perhaps the easiest kind of team to consider- though they can be the hardest to make work across all situations, rather than only in certain ones.  A focused team is a team where each member of the team operates a certain way- and because they all operate that way, the team is especially good at it.  While it’s easy to come up with a group of six tanks, six sweepers, six walls, or six tricksters, it can be very difficult to form them into a team without a glaring weakness that simply begs to be exploited.

A team of tanks is utterly lacking in member variety- if one sweeper manages to start breaking your team- especially if that sweeper sets itself up with stat boosts first- then the game’s most likely over.  If one wall manages to boost itself up well enough or even simply rack up enough residual damage from hazards and status moves, you’ve been doomed to a slow loss.  Even worse if a team of tricksters manages to afflict horrible status on all of your team members- with all of them functioning alike, anything that beats one of them likely beats all of them.

Similarly, most teams of walls will lack any way to break through an opposing team that is tough enough, resulting in a long stalemate.  A team entirely of sweepers will not be able to handle a sweeper in return, and can fall to a single effective trickster.  An entire team of tricksters will tend to be really fragile, and even the slightest failure of your luck can leave your team toppled.

Because of this, every member of a focused team needs to be capable of breaking focus at least a little bit.  A team of tanks who all have attacks that may boost their stats, allowing them to sweep or wall, will stand a better chance.  A wall team where every member has at least one direct actual attack will not be stopped entirely by Magic Guard Clefable or other such nonsense.  A sweeper team that has paralysis and sleep available to it, or that includes a member who can toughen themself into a borderline wall will be able to endure through tough times, and a trickster team that stacks attacks with its status will operate much faster and have to take less hits.

Because of this, a focused team is both an advantage and a disadvantage- As the team members all act the same, it is easy to continue operating it and maintain its momentum.  However, as the team members all act the same, anything that ruins one of them may well ruin the lot.