Here is the list of plans that might show up in the story. The discussion on endbringers was very fruitful, so this won't be the rambling monstrosity my other post was.
Twist em Up
Teleport endbros to space/a dead world, use TSAB superweapon.
What we need to do...
Position the superweapon.
Teleport the enbringers.
Why this will be useful...
Kill the endbringers, avoid collateral damage.
Problems...
Getting enough mages trained in teleportation.
Slowing down the endbros enough to teleport them.
No Kill like OVERKILL
Make several superweapons to kill endbringers. You never know what might go wrong.
What we need to do...
Get some Tinkers together and make superweapons.
Why this is useful...
More options in case something goes wrong
Eternal Jail
Find ways to imprison/trap the endbring
What we need to do...
Get some Tinkers together and build; also, find time manipulators and parahumans who can do this
Why this is useful...
If we permanently imprison them, they are no issue. Even if we can't permanently imprison the endb, bind attacks are useful.
Problems...
Developing the tech can be handled off screen and with voting.
Finding parahumans with such powers is trickier. Many Parahumans might not cooperate with us, and some useful powers aren't immediately obvious.
Hurt The Enemy
Hit the enbringers with buster attacks, or find parahumans with very potent offense, like Foil or Damsel of Distress.
What we need to do...
Train more mages to have buster attacks.
Make efforts to find parahumans with potent offense.
Why this is useful...
Hitting the endbringer core is one way to defeat them. How do you expect to do that without any firepower?
Problems...
Training mages is no problem. Finding someone with a high level Linker Core? More problematic, although templates will solve that. Getting someone willing to fight the endbringers might be more difficult.
Most Parahumans don't attend endbringer fights, and people with extreme offense are very rare.
Negotiate-ask cassiel
We don't know if this is viable. All we can do now is ask Cassiel if the endbringers can be negotiated with.
In Summary
With tinkers...
Start building superweapons, like the nanite cannon.
Start building things that stop/trap endbringers.
With other Parahumans...
Start a recruitment drive for parahumans to join the endbringer fight in general, but look especially for capes that can slow down or hurt endbringers.
Hell, even if such Parahumans don't want to join the fights, tinkers can still study their powers for inspiration.
With aliens...
We will need to coordinate with the aliens if we are to implement Twist em Up.
With mages...
Recruit and train mages to get the teleportation down.
Train mages to use buster attacks.
Really, just get more mages to attend endbringer fights. We need warm bodies.
With Cassiel...
Talk and see if negotiations are possible. Not likely to work, but we lose nothing from asking.
Edit: This is going to be my last summary of enbringer strategies. I want to discuss these more with you guys, but damn is it hard to type all this out.