Strategies for Defense

I've been playing CTF for about three years now, and have always been a defender. I thought it'd be good to share some tidbits I usually follow whenever defending whilst playing CTF.

• Ninja isn't a good defensive class, it's usable but there are better options for defense. This is because Ninja excels in rushing the enemy and dealing massive damage whilst dodging hits, but on defense this usually leaves Ninjas as bait. Only use ninja on Defense if you have allies defending with you, preferably something bulkier or something that can slow the enemy down
• Pyro is the best Solo defense class by far, it hard counters almost every capping class that approach. Being mobile as Pyro is essential, as well as using your flint and steel properly. Chase soldiers out of the flagroom and wait until Chemists go in to attack you, approaching a chemist tends to get you in messy situations while Soldiers have little to no means of defense against you rushing them.
• Mage and Chemist are great for supporting flag carriers, Chemist has the AoE of damage potions to drive enemies attacking the flag carrier while Mage can easily lightning away any enemies or shoot them. Both classes also have a means of healing the flag carrier.
• Chemist is the best all around defensive class. As a Defensive Chemist, don't rely on pots for your damage output. Many chemists die because they're too oriented on using their damage potions. Damage pots should be used every so often but not in quick succession as the damage is minimal by potspamming. As a Chemist, stay mobile. Kill enemies outside of the flagroom as well as deal damage to anybody grabbing the flag. Also, throw a poison pot often at the flag to scope out any enemy Ninjas.
• Assassin is like Ninja but worse, only use it if there are quite a few people on defense.
• Engineer is meh on Defense, it's much better on offense since it can transport allies very far.
  
• Using the Earth Spell as elf on the flag is useful at slowing down any players trying to grab the flag
• Medic is a staple defense class, Defense is exponentially stronger with one
• Dwarf is good for flagrooms with few entrances as Assassins are easier to block.
• Mage is good for defense, use it in a similar fashion you would as chemist.
• Stay at the flag at all times if you are a staple part of the defense (The Pyro/Medic of the defense), many defenses crumble once somebody gets the flag as they try to recover, which ends up making the flag much more vulnerable when it comes back
• If defense is strong, don't overcrowd it. Fight enemies outside of the flagroom with Chemist or another high damage class, Heavy is good too as it can take hits and act as an obstacle before they approach the flag
• If the defense is strong, you can also help the flagcarrier return to your side. Most of the time the flag carrier just needs a Mage or Chemist distraction to impede the herd of enemies jabbing at them.
• Change class often if you are not a staple defender, it is much more effective to clear your flagroom with Assassin when overrun than trying to continue using the same class. Adapt to the situation.

That's all I've really got for now, a good defense makes a great offense.