you do know that hyper beam always requires recharging in stadium, yes?
i wouldn't take jynx because each of her roles seem to be redundant with something on the already solidified aspects of your team - you've venusaur as a sleeper, gyarados as your attack spammer [which has blizzard, though you're right about it not being STAB, but it /does/ get STAB surf and has higher special...], and jolteon for your speed. every single one is capable of taking hits better than jynx is, and has other utility [venusaur has that always-critting razor leaf and the always-helpful chance to para in body slam, gyarados is weak only to electric and is mixed [though i guess defensive synergy doesn't particularly matter with jynx as she pretty much dies to a burp unless it's resisted, weak and special], and jolteon can easily spread paralysis and reduce accuracy if needed]. stab blizzard is definitely nice, not going to downplay that, but it's not that necessary. the only thing coming to mind that i really see you needing it for that isn't really covered by anything else is exeggutor and jolteon's pin missile is okay with that too - aside from that tasty freeze rate. but you've got a lot of paralysis on your team + a sleeper + another blizzard user, so it's not too crucial.
tauros is indeed the king of rby and although is not as mandatory as snorlax in gen 2, a team can't really get worse with a tauros on it, and he helps a lot with that great crit rate and coverage. rhydon is as you said a great normal resist and is also a pretty good hard-hitter on its own, despite its crit rate being crap.
yeah not having jynx makes your team weaker to fighters but who the hell cares, really? venusaur and gyarados should do nicely against them. fighters are not that threatening in first gen.