>>21208669Yes, but if you don't stop the sweep, you lose the game. If you use Twave, you cripple the sweeper for the rest of the match, possibly render it useless if it's frail, and all you lose is Thundurus.
That's better than having the sweeper tear huge chunks out of your other mons, or KOing something else.
The point is that, in most cases, they'll switch out the sweeper and try again later when you bring in Thundurus. If you're playing against a good player, simply having Thundurus on your team will discourage the opponent from trying to set up, because they know that they'll be stopped.
In other words, you don't have to worry about your opponent setting up if you have Thundurus. This gives you one less thing to worry about, lets you make more aggressive plays (because you know that the opponent can't capitalize on any free turns you might mistakenly give them), and can make them play more defensively (don't want to give it a free switch to paralyze something, for example).
Thundurus's presence has a huge influence on how the opponent plays, and it's arguably broken because Thunderwave is such a catch-all stop to everything. If you're an attacker that relies on Speed and you're not Ground or Electric-type, you're checked by Thundurus.
