See, to me that just sounds like a silly workaround to the root problem: stuff getting buffs that are basically immune to Dispel, which brings us back to square one of "we need things to not be immune, dammit". The whole point of dispel is to get rid of a foe's buffs, but now we're just seeing foes that have permanent buffs so Dispel becomes pointless.
Well these buffs don't work along the same lines as dispel. As you said "Buffs that are always on." Perhaps in this case the lockdown spell can serve like a Dispel II that works for this category of ability, or even prevents the monster from receiving further bonus effects when they use an ability.

So dispel removes buffs currently on the mob, and Lockdown prevents buffs more from being placed on the mob for a certain duration.

For TP moves, I feel like all the ideas we've come up with trend towards simply making the TP move not happen. I think instead we might want to start gunning for something a little different. Addle reduces magic accuracy right? Why not extend that aspect to TP moves. Add something that severely reduces the potency of the TP move. They'll still be going off and TP feed is always going to be a concern, but instead of one-shotting that Tarutaru in the crossfire it'll instead knock his health in half. Just some sort of Damage Dealt -X% effect, or something along those lines.
Addle also delays the casting of spells, so why not extend that to delaying the use of TP moves? More time to stun, more time to get that sudden Cureskin on your tank. Gives your Melee an opportunity to get out of range, etc. I'm on board with the secondary effects as well but just giving players more time to react to incoming TP moves would be incredible.