need details on the set though
Apologies I forgot to screenshot, but the set was Volt Switch, Flash Cannon, Toxic, Thunder wave.
This set just does not function with magnet pull in place. Toxic is ineffectual against steel types in the first place. Then you have the issue of flash cannon not working against any steel type that doesn't share a rock or ice type. Most of these pokemon take 10-20% on a flash cannon and hit back much harder. Volt switch is a fine move if you can either outspeed or live a hit, but on pokemon that might have a ground or fighting move, you'd be taking a gamble. Thunder wave is an okay move if you can get it off, but the problem is threefold: 1) Only 24% of steel types are actually outsped by probopass. 2) Pokemon that are outsped by probopass really aren't fantastic recipients of paralysis. 3) Of the steel pokemon that probopass doesnt outspeed, 57% of these pokemon have a better than even chance of carrying a dangerous move in the first place.
The issue here is not that magnet pull isn't useful. In some games it absolutely can be a crucial element to your strategy because the opponent is forced to play their steel type around yours. The issue I see is that it's far far more likely that you'd rather just have Sturdy.
Consider this rough math. I've averaged all the percentages from my spreadsheet to be that a given steel type has a 45% chance of carrying a super effective move. The opponent gets 6 pokemon from a pool of 904 different pokemon and forms with an equal chance of getting any of the 43 steel types. The odds of the opponent having a single steel type are about [(904-43)^6/(903!/898!)] or just around 75%. There are only 21 steel types probopass reliably 2HKOs, and of those only 4 have a chance of being OHKOed. That's about 50% of steels that probo deals with.
These numbers broken down:
In 25% of battles, magnet pull is worthless as the opponent has no steel types
In 33.75% of battles, magnet pull will trap a steel, but the steel has a move that seriously threatens probopass
In 20.625% of battles, magnet pull will trap a steel that does not have a threatening move, but probopass will also not secure the 2HKO
In 20.625% of battles, probopass safely traps and dispatches a steel type.
All of these statistics were made even before factoring in whether or not probopass has the appropriate damaging move in the first place. If I estimate and assume the best move is always earth power (or volt switch; they have the same chance of being drawn), that last figure then becomes 33% lower at a staggeringly low
13% chance for magnet pull to succeed.
Now YES, this is a gross oversimplification of matters, but I wanted to show just how many things have to go right for probopass to actually have this ability work in its favor. Obviously you'd be well within your power to keep probo in against a pokemon that threatens, and obviously air balloon does complicate things in probopass's favor. But still, when compared to the universal utility in Sturdy, I can't say that probopass deserves to be running what it currently is. I encourage you to check my math and let me know if I've committed any errors or made too big of a logical leap anywhere, but as it stands right now, I dont think probopass should stay as he is when his ability doesn't work 90% of the time.