I like Rosa's distinction between 'intent to lose' and 'intent to handicap'. It's easy to bring a normal-looking team, click a bad mon, and then make up some inane reason for your choice. This is what the majority of people will do if they really intend to throw the battle. Obviously, this form of throwing is bad and should be punished in any context, for reasons that need not be explained. I think everyone agrees this wasn't the case with mishlef, who'd have thrown the game earlier and in a less overt way if he'd wanted to.
Much more common are people who, for whatever reason, limit themselves in terms of teamslots, mons, moves, or whatever. I honestly don't care much about situations like this, and it's extremely unclear what even counts as sufficient 'intent to handicap'. Tournaments have featured people using LC mons, triple D-tier teams, 2-mon teams, monotype teams, or the same team they used every single other match, and while some of those were made with the intent of winning, some were obviously just people messing around. If someone wants to storm SSNL with mono dragon, more power to them: I don't see the point in tolerating it in lower rounds but turning it into a problem when they make it to the upper ranks. Whether Mish 'g5 mono aroma' Lef's dumb stunt paid off or not (spoiler alert: it didn't), as long as he was trying to win I don't see an issue with it. Strats like those will just cause you to be eliminated somewhere along the way, and if they don't then the issue is really with every other player, tbh.
An important exception to the above: in team tours I 100% think that 'intent to handicap' is a punishable offense, for the simple reason that people get put on a team in the understanding that they will play optimally (or at least, not deliberately hamstring themselves) for that team. This also lets us bypass the problem of defining 'intent to handicap' by using the opinion of the other players on that team: if a player brings mono aroma g5 despite all their teammates disapproving, I'm completely in favor of letting that team push for a tourban or other punishment.