Unfortunately, you're going about this the wrong way. We don't write analyses and then debate the mons, the mons only get analyses when it's agreed that they are viable and ranked. Currently nobody believes that pupitar and Lairon are viable, so to get permission for analyses you'd have to prove their worth first. The only advice I can give you for this is that you're wasting you're time. Pupitar have slightly different stats and moves doesn't give it a niche, the unique things it has that you've outlined (dragon dance, better special defense) don't actually make it worth using over the multitude of similar mons in the tier. Lairon similarly has no good reason to use it. The best way to convince anybody of this would be replays with good teams vs good players showcasing where the mons perform a useful, relevant role that nothing else could, but frankly you'd be wasting your time trying to find that. There is no approval for this
Try Tank Golem, even tho it isn't a sweeper it can fulfill the roles you want it due to its amazing role compression.
The issue with this set is that Castform's stats are just too bad for it to be worth using despite its amazing movepool. It's still very slow even with max Speed and it's awfully frail, which means that it will usually not even be able to get rain up and will almost never be actually able to attack, unlike Electrode which is fast enough to make up for its frailty. Getting rain up is vitally important and it's really hard to consistently do when you have things like these in your way:
