Need help tweaking my team

[LittleTutwo]

Hello, so far the team has been doing well for me. However, whenever I face fire or dragon types I have trouble so I feel like the team needs a little tweak or a different Pokemon added but I'm not sure what. Any help would be appreciated, thank you!
My team currently is:

Rotom-Wash
Nature: Bold
Ability: Levitate
Item: Leftovers

• Volt Switch
• Hydro Pump
• Defog
• Will-o-Wisp

Charizard-Y
Nature: Timid
Ability: Blaze

• Roost
• Solar Beam
• Focus Blast
• Flamethrower

Jirachi
Nature: Jolly
Ability: Serene Grace
Item: Choice Scarf

• U-Turn
• Wish
• Iron Head
• Fire Punch

Tangrowth
Nature: Bold
Ability: Regenerator
Item: Leftovers

• Earthquake
• Giga Drain
• Knock Off
• Sludge Bomb

Ambipom
Nature: Jolly
Ability: Technician
Item: Life Orb

• Fake Out
• Low Kick
• Return
• U-Turn

Kommo-o
Nature: Hasty
Ability: Soundproof
Item: Leftovers

• Clanging Scales
• Close Combat
• Poison Jab
• Stealth Rock

Thanks for any advice.

 

[Levea]

From inspection Aside from the threats you stated ( fire and dragon ) this team gets shredded by ash-greninja dark pulse. I recommend swapping tangrowth for a tapu-bulu spdef set to offset this. I am also thinking that heatran would work in tandom with bulu swapping out the jirachi. this way you have a defensive core between bulu, rotom, and heatran that covers a decent chunk of your threats rotom and bulu covers the earthquake switch in in case rocks are up. bulu pretty much switched in on rotom's threats and Heatran switches in on dragon and fire moves while getting passive regen from grassy terrain. Also you could switch Ambipom or Kommo-o ( Probably the former ) with choice band tyranitar with pursuit in order to trap and eliminate Latios/Latias and other threats that are weak to dark and rock from the game board. Also, If you are looking for a reliable rocks user I am not sure if kommo-o is that reliable considering I think it's best uses are more geared toward offense ( Kommo-o Z crystal or salac berry belly drum etc). Good rock setters include the after mentioned Heatran. This leaves you lacking a form of speed control. You could add Kartana to capitalize off of bulu's terrain and increase your match-up vs. offense or you could add scarf lando to create a volt-turn core to gather momentum and bring in your threats. considering the type of team that I have laid out I would recommend something that can outspeed things and act as an alternate win condition ( kartana would do this well ).