Strategy For Defeating Pike
Pikes are fairly fragile and can be destroyed by a solo player, but if you kill the rider the Pike will stop moving and become player-capturable.
Pikes are capturable in the Secret Public Event Pike Gang. Just wait for the gang to arrive and then use small arms fire to kill the riders - try not to do heavy damage to the pike itself, because they cannot be repaired.
Left-click (on PC) to fire the cannons, right-click to fire the jet thrusters, and hit space to get off of the pike. Pikes cannot jump, but can be flown off of cliffs, and do not protect their rider from fall damage. A stolen Pike is quite the mobile weaponry platform, but cannot destroy certain event targets like Arsenal Walkers or Elite Ether Servitors, but is otherwise excellent for killing standard (and heavy) foot troops.
The twin cannons on the Pike have a very high fire rate, but after a five or so seconds of sustained fire will slow down. If you stop firing and let the cannons cool, you can open fire with the full refire rate for another burst of heavy fire.