Engineer match-ups

From TF2 Wiki

Class			Threat	Strategy
Engineer	v	Scout	Low - High	A Scout is a more threatening opponent when on your own. Try and stay out of point-blank range, and blast them with your Shotgun while avoiding their Scattergun shots. It is better to avoid direct combat with an experienced Scout as their Scattergun can do much more damage (and can instant kill at point blank if it crits) than your Shotgun. When with a Sentry, you can relax, as it will mow down any Scout relatively quickly. While scouts cannot dodge or outrun the bullets of a sentry, at certain ranges they may be able to run to cover before the sentry can turn to face them. This can often be avoided by placing the sentry so that its normal 90° sweep covers the right area.
Engineer	v	Soldier	High	For lone encounters with a Soldier, don't try to fight unless he is severely weakened or you know you can safely take him out with a single blast with your Shotgun. It is safer to run, or lead him into your Sentry. Be wary when guarding your Sentry, as Soldiers can use their Rocket Launchers to destroy an Engineer's equipment with a volley of successive shots. Keep it well repaired, and be sure to place yourself behind it to minimize taking splash damage from rockets. If you can, help your Sentry do its job by firing on the Soldier with your Shotgun or Pistol.
Engineer	v	Pyro	Medium - High	When on your own, stay out of range of a Pyro's Flamethrower and blast away with your Shotgun, or, at longer distances, your Pistol. However, if you have a Sentry, it should be able to mow them down quickly before they can get within effective range. Try not to place your Sentry so it hugs a corner as this allows the Pyro to take it out without entering its line of sight. Bear in mind; if pulled off correctly, a skilled Pyro can circle strafe to take out a level 3 Sentry, you, and all your buildings without dying. So long as the Pyro isn't allowed to get your sentry into the range of its Flamethrower, it won't be a threat to your building. Keep an eye on your health if you catch fire, and retreat to a health source such as your own dispenser if your life is in danger.
Engineer	v	Demoman	Very High	Like Soldiers, Demomen are a very dangerous class for an Engineer and his Sentry. They can lay down sticky bombs and grenades while staying out of your line of sight, which can take both you and your Sentry down quickly. Sticky bombs are especially deadly to your buildings; to remedy this, try and avoid placing your Sentry around a corner or in a vulnerable position. If a Demoman is about to sticky your sentry, take the fight to them with your Shotgun. In a one-on-one fight, stay at medium range while blasting away with your Shotgun.
Engineer	v	Heavy	Medium - High	A Heavy can use the high rate of fire from his Minigun to destroy a level one Sentry, and even take out higher level Sentries when paired up with a Medic. To remedy this, stick with your Sentry and keep it well repaired until it takes out the Heavy, and hopefully his Medic partner as well. If they are ÜberCharged, do your best to keep your Sentry repaired until the charge wears off. If it is clear that you cannot save your Sentry, it's better to run, and live to fight another day. In a one-on-one encounter, it is best to flee, as a Heavy will likely mow you down before you can take him out with your Shotgun.
Engineer	v	Engineer	Low - Medium	In a one-on-one encounter with an enemy Engineer, simply blast him with your Shotgun before he can take you down with his. As an Engineer, you ought not - usually - to be in a situation where an enemy Sentry gun is a major threat to you.
Engineer	v	Medic	Medium - High	Medics, alone, are fair fodder for your Sentry, but when using an ÜberCharge, they can spell danger for an Engineer. Simply keep your Sentry repaired until the charge wears off and it will hopefully take out the Medic. Should the Über-team come close enough to put you or your sentry in terminal danger, bail out immediately and prepare to rebuild when the action dies down. In a one-on-one fight, avoid their Syringe Gun shots and Bonesaw while blasting away with your Shotgun.
Engineer	v	Sniper	Medium - High	It should be rare that a Sniper is within close enough range of your Sentry to be killed by it, and on maps where it is more difficult for a Sniper to reach your position, you can expect to see very few of them. On more open maps, however, a Sniper is more dangerous as he can stay out of range while damaging your Sentry with charged Sniper rifle shots. To solve this, stay with your Sentry and keep it repaired. At close range, blast the Sniper with your Shotgun, while avoiding his Kukri and Submachine Gun shots. The Level 3 Sentry provides modest cover from headshots, but at times you benefit most from setting up in a spot safe from sniper fire. Be sure to alert your team when a sniper targets your sentry.
Engineer	v	Spy	Medium - Very High	A skilled Spy in disguise and his sappers can act to counter you, but as long as your teammates are around you and you're alert, they shouldn't pose as great a threat as they would do. Spy-check anyone coming within range of your Sentry, and listen carefully for the decloaking sound that Spies make. If a Spy places sappers on your equipment, your top priority is to remove the Spy, either by yelling to your teammates for help or blasting him a few times with the shotgun. When the Spy is no longer a threat, remove the sapper immediately (by hitting it with your Wrench) to prevent further damage and repair. Be warned that a Spy can sap faster than you can repair, so if you don't take him out, he will eventually destroy your equipment. To prevent surprise stab-saps, it's useful to glance over your shoulder between Wrench-swings as you build or repair one of your buildings If a Spy saps a structure when you're too far to save it, inform your teammates and keep your guard. Remember that the Spy is much less effective when your team is actively pursuing him.