Why do you only have 3 Pokemon? You really need a team of 6.
As for Janine, she's actually a pretty easy trainer. I would say the only person easier is Erika, but since you have 3 Pokemon, that's why you're struggling.
I think you should give your Pokemon a Persim Berry to hold & they'll snap out of confusion instantly to buy you a turn or two. All things considered, Typhlosion should be faster than her Crobat since it's only L47. If you're still slower, gain a level or two in order to out speed it. Bring some Antidotes and/or Pecha Berries to counter her Toxic. Try and use a move that will do slightly more than half damage to her Crobat so that she doesn't use a Potion on it.
Watch out for her Venomoth because it can mass spam Double Team on you and then sweep.
Her 2 Ariados should be fine for your Typholsion, just use Flamethrower on them (not Blast Burn because you need to recharge and that just gives Janine an extra turn. Actually don't use Blast Burn against her at all, or indeed any other gym leader/ champion).
As for Weezing, you're either going to have to tough it out with Typhlosion or Zen Headbutt it with Slowbro. Her Weezing also has Explosion, so it'll wittle your HP away with Toxic and then Explode on you to take out one of your team.
I would also suggest Headbutt for Typhlosion over Rollout since it's such a horrible move. Headbutt can be taught to you by that guy in Ilex Forest, and at base 80 + 30% flinch, it's a really great in-game move.
I suggest you get a Ground type like Mamaswine (get a Swinub in the Ice Path in Johto), an electric type like Ampharos (get a Flaffy on Routes 42 or 43 in Johto)/ Magneton (get a Magnemite in Routes 38 and 39 in Johto), and a grass type like Vileplume (get a Gloom on Route 47 in Johto). The downside on Magneton is that it cannot evolve into Magnezone in HGSS unless you trade to DPPt.
I would also recommend Togekiss (you did get that Togepi Egg from Mr. Pokemon after all), and Gengar (but you need to trade to evolve it). If you can't trade, then get a Misdreavus in Route 47 in Johto & use a Dusk Stone on that.
You really should have 6 Pokemon by now, especially for a game like HGSS since the level curb is ridiculous and it takes so long to train a Pokemon that you need to face Red under levelled.