hello,
         the team looks like an ok zard y + band tar team. however, it lacks hazard removal and has no real set up sweeper. the team is also fairly slow in general, and would appreciate a couple of ways to outspeed threats. ash-greninja and scarfed(or any) keldeo look like the biggest threats to the team.
          the first change that i would recommend is to run sand rush excadrill > scarf scizor. excadrill helps to give some speed in sand, and is a more reliable check to pokemon like tapu koko. scarf scizor isn't really very viable, and sand rush excadrill has much more utility, being a great win-condition and bringing in pokemon which zard y comes in on. some examples of these include tangrowth, celesteela, and landorus-t.
          the next change that i would recommend is to run rocks jirachi > magearna. this gives excadrill and tyranitar some healing wish support, while still checking pokemon like tapu lele (a little softer but still does the role). this also prepares for a future change.
          the last major change that i am going to recommend is to run calm tapu fini > landorus-t. running calm tapu
fini will help the matchup vs non grassium z ash greninja and non normalium z hyper beam keldeo. what you have mentioned is that it checks offensive landorus-t and scarfchomp. however, rocky helmet tangrowth is solidder for both. tapu fini also helps vs zard x and helps with the stall matchup in general.
          moving onto minor changes, running fire blast > flamethrower on charizard-mega-y. this maximizes damage output, which is very helpful for a pokemon which likes to hit as hard as possible.
tl;dr
[IMG] > [IMG]
[IMG] > [IMG]
[IMG]  >  [IMG]
[IMG] (fire blast) > [IMG] (flamethrower)
Importable
[HIDE]
Tangrowth @ Rocky Helmet
Ability: Regenerator
EVs: 248 HP / 212 Def / 48 SpD
Relaxed Nature
- Sleep Powder
- Giga Drain
- Knock Off
- Hidden Power [Ice]

Charizard-Mega-Y @ Charizardite Y
Ability: Drought
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Fire Blast
- Solar Beam
- Roost
- Focus Blast

Tyranitar @ Choice Band
Ability: Sand Stream
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Stone Edge
- Crunch
- Superpower
- Pursuit

Excadrill @ Life Orb
Ability: Sand Rush
EVs: 4 HP / 252 Atk / 252 Spe
Jolly Nature
- Earthquake
- Iron Head
- Rock Slide
- Swords Dance

Tapu Fini @ Leftovers
Ability: Misty Surge
EVs: 248 HP / 176 Def / 16 SpD / 68 Spe
Calm Nature
- Taunt
- Nature's Madness
- Moonblast
- Defog

Jirachi @ Leftovers
Ability: Serene Grace
EVs: 252 HP / 200 SpD / 56 Spe
Careful Nature
- Iron Head
- U-turn
- Stealth Rock
- Healing Wish
[/HIDE]