An "easier" way to program multiplayer games?

Depending on what you need, it might be more convenient to use MPGET and MPSET. Each terminal (i.e. each 3DS) has 8 (or 9?) variables that it can set, and other terminals can read these values. So for example, each player's health will be saved to his first network variable: MPSET 0, HP then everyone can see every player's health:

P1HP = MPGET(0, 0)
P2HP = MPGET(1, 0)
P3HP = MPGET(2, 0)
P4HP = MPGET(3, 0)

This system isn't perfect for every situation, but it's very convenient for storing player-specific info that is required on every player's console. It's also important to remember that only integers are allowed, not floating-point numbers. http://smilebasic.com/en/reference/#wireless

Thx, you saved me about 16 lines of code :D

There are 9 variables. And updates to the variables are not guaranteed to be detected in order. In other words, say you have one variable which is a counter of cumulative HP regeneration, and another which is cumulative HP damage. One console may increment its 'regen' counter just in time to survive a damaging hit, but other consoles may see (for a moment) values indicating the player should die. So, as much as possible, put independent values, independent aspects of the game, into different variables (or, use a communications protocol) to avoid such glitches and inconsistent game states.