Always reach the objective before Terminus and place one turret on the enemy side. This way if terminus stays on the point and uses his siphon your turret will keep doing damage and force Terminus to stop using siphon to destroy turret or move back.
In a 1v1 situation, silence him with running blast and deal damage until he uses emitter, then channel recharge towards him until he runs out of shields then finish him. Nimble would be perfect to keep pressure on him if he tries to run away.
Andro is one of the best counter champion to Terminus. You can absorb his ultimate using reversal and fire back for instant kill. Also whenever terminus uses his siphon use dashes to move behind him and shoot him from behind for easy kill.
If Willo uses her skills wisely, you won't be able to beat her up close. At first you should find higher one than her position that you can suprise and chase her out of. Willo is not very good at dealing with flying or high mobility enemies.