Below are the tips of the selected levels.

LEVEL 1

Best perk: Hyper Healing Perk

Quite easy level to complete both Bonus Objectives.

Best plant: Shrinking Violet

- Shrunken Weasel Hoarder cannot release Ice Weasels.

- Shrunken Troglobite cannot push ice blocks.

- Synergizes perfectly with Draftodil (for stun zombies objective) to blow off shrunken zombies.

- Imp Pear is fine but it only aims at single zombie at a time.

LEVEL 2 | Last Stand

Best perk: Penny Multi Shield Perk

As for new game update, Octo Zombie can aim at Lily Pad (without plants).

Use a melee plant (Pokra / Bonk Choy / Bamboo Spartan - only for early access, etc) to destroy octopus before Octo Zombie can throw a new octopus.

LEVEL 3 | Vasebreaker

Best perk: Bass Blast Perk

Ignore Hypno-shroom!

LEVEL 4

Best perk: Bass Blast Perk / Jalapeno Pepper Perk

First 5 plants are pre-picked:?

For Spicy difficulty, recommended plants for seed slots include: Chilli Bean, Imp Pear.

Yeti cannot be knocked back and hypnotized.

LEVEL 5 | Conveyor

Best perk: Bass Blast Perk

Impossible to kill Caesar Zombie with low-lvl Red Stinger, Ghost Pepper and Citron.

Chill Zombie objective is possible by stalling as many zombies as possible at one lane, then repeatedly apply Hurrikale to that lane.

ZOMBOSS | Zombot Tomorrow-tron - Far Future

Zombie level: Lvl 1 / 4 / 7

Zomboss health bar: 7 / 9 / 11

Seed slot: 7 / 6 / 5

Locked plant: Ail-mint

Best perk: Bass Blast Perk / Hyper Healing Perk (with Chard Guard)

Quite easy level in general.

Bowling Bulb strategy is generally the best even at low lvl (boosted by Appease-mint).

Plenty of Plant Food-carrying zombies.

Sun-producing plant is required, there are not many suns dropping from the sky.