i could see mandi in a rn, it's really a lot better than people give t credit for. if you ev it correctly it can tank two focus blasts from lando and becomes a solid lando check, it can handle stuff like chomp, +1 dnite, +1 char x (though it's almost saccing itself to do so unfortunately), revenge non-jolly boosted bd azu given it has 16 speed evs to outrun it, exca, standard aegi, deo-s, bisharp, mega scizor, tflame, loom...it handles a lot of common stuff well and can provide pressure between foul play + taunt/toxic(/knock off), doing really well against common threats, especially being a solid answer to lando not weak to pursuit. it provides immense team utility in defogging too, it can actually deal with bisharp too which is really good for a defensive defogger. if we're looking at other a- defensive threats, we have skarm and chansey (rotom-w kinda but it's more like a pivot). chansey is limited to a sole playstyle, stall while mandi is really good on teams across the defensive spectrum, including as you go into lots of balanced teams where mandibuzz really shines. skarm isn't necessarily limited to stall, but mandi is much less of a sitting duck, as instead of just sitting there and tanking stuff it it is actually able to be more proactive and smack stuff with foul play and w/e. if you look at a we have ferro, hippo, and heatran, which cover a variety of relevant, significant threats like mandi and can actually be proactive vs these threats while providing different varieties of team support. mandi fits there nicely imo.