Your sustain means nothing when Willo uses deadzone on you, your best bet would be to approach her when you have darkness to out damage her in the short run, in the long run of a fight Willo will almost always win

Io's ultimate provides her invulnerability for a prolonged amount of time if you are trapped with a Terminus resurrecting using the ult to invuln through it, similar to Androxus' Reversal you can use your ult to wisk Term away before he can react.

Androxus' reversal isn't able to counter either, Guardian Spirit stun or Begone but his damage per second and having burst damage allows him to clean up kills on Io fairly Quickly. This is not to say that Io cannot body block with Luna.

most champions will have a hard time dealing with Io and Luna together, so don't engage them together instead try to single out Luna while Io isn't around, so when it comes time to kill Io she can't stun you or body block with Luna.