1 and 2 are powerful enough already
3 (kamikaze) sacrifice it plus a bomb to take out any opponents piece on the board from anywhere
4 (air lift) can switch places with any one bomb or flag (once per 4, per game)
5 (marine) can walk over lake squares
6 (paratrooper) can jump over another piece (of either team)
7 (guerrilla) can move/attack diagonal
8 (bomb squad) can dismantle bombs (as in original rules)
9 (stealth scout) can move and strike on same turn
S (sniper) if it reaches last row (closest to opponent) becomes superspy.
Superspy beats all number pieces - but only if it strikes first. It loses to everyone when defending.
Of course no piece has to use its abilities, and using them will reveal which piece it is.