I think it has been pretty well covered so far, that Vulpix is actually not dead weight on a team, and is in fact actually quit useful outside of providing sun for Tangela. But Vulpix is also actually really specially bulky, with only Ponyta having higher special bulk, while Vulpix has the benefit of being psuedo-neutral to water, eviolite Vulpix is also really hard to switch into thanks to W-o-W and a sun boosted Fire Blast, while being hard to wear down, thanks to its bulk and Pain Split. So no, Vulpix isn't a trash mon at all, it has a niche even outside of being a suicidal sun setter or w/e. That being said, if Vulpix was a trash mon it doesn't even matter, Tangela definitely does enough work in 4-7 sun turns to count for 2+ pokemon. (This is where Electrolyte ninja'd me and made my post look dumb :/). Tangela's power, utility, and abilities make it broken beyond any doubt, and it is quite obvious that Tangela was not originally designed to be and LC mon.
Anywho, I haven't talked about Yanma at all yet, so I would like to comment on that. If Yanma only had access to speed boost, I think that we could all agree it is definitely not broken, as that set has definite Checks / Counters in Archen, Misdreavus, Gligar (if no HP Ice), Magneton (if no HP ground), and more. However, the Compound Eyes Hypnosis set is almost impossible to switch into and has a completely different (and smaller) set of counters. Hypnosis (in conjunction with Compound Eyes) is the best sleep inducing move this gen in terms of what it affects, as grass types and overcoat pokemon are not immune to its effects. This means that the only way to avoid being put to sleep from hypnosis is from Insomnia, Sweet Veil (only Swirlix avoids sleep, not teammates from what I have read), or vital spirit. All viable users of these abilities (all of the users) are 2hkoed by by Yanma's STABs alone, and all are outsped by Yanma except Elekid which must rely on a speed tie. Sleep Talk users such as Munchlax and Chinchou seem like a decent option to take on Yanma, as they are both decently bulky (mostly Munchlax), but with Hypnosis + U-turn, Yanma can simply sleep them and then gain a ton of momentum. The fact that it is SR weak isn't much of a factor when plenty of good pokemon in LC can provide defog support with ease (read gligar). I'm not necessarily convinced, however, that Yanma is broken as sleep time is shorter and Yanma has problems sweeping entire teams once it has put something to sleep. It does seem to be an issue thought, that you have to sacrifice one thing to sleep, and more than likely something else switching in on Yanma, if it gets in once.