Pvz 3 tier, upgrade and unlock plants system

Plants 

common: can be unlocked by beating levels repairing or upgrading structure or completing bonus or challenge levels/quests

rare: same a common 

epic: can be unlocked by beating levels upgrading the main structure of certain area or hard quest levels

legendary can be unlocked through beating challenging levels/bonus levels and through in game currency (only one can be played on the field per level) and limited edition events

mythical same as legendary but can only bring one mythical seed slot:

zombies 

common: basic zombies with no abilities or not super impacting abilities (example buckethead zombie)

rare:zombies with a good ability or very good health and or speed example Garg or bowling zombie)

epic: insanely good ability example pigeon feeder zombie

legendary insanely op that only one can be on the field at a time

upgrade system

every area has things you can upgrade the main structure like Dave’s house and there are other structure around as well between 3-5 bonus structures per area

structures can be upgraded through coins, gems taco tickets and other currency

main structures has 5 levels and other structures have 3 

main structures are more expensive but most of the time more impactful like new plants buffs and abilities

smaller structures are cheaper but still worth to do because it can give you coins over time can give common and rare plants coins and other minor things

and since this game is about customization the plants could have instead of levels they could have different tier offer both buffs and nerfs. 

for example tier 1 peashooter 10 shots to kill a browncoat and 4 sun but tier two would be changed to six shots to kill a browncoat but cost 6 sun instead of 4

U can use the piñatas to unlock a plant and but these tiers. When a tier is unlocked you switch back and forth

for no cost

common-epic plants have 3 tiere

legendary and mythical have 4-5 tiers

common plants 1 seed packet to unlock 10 packets to unlock a tier

rare 6 packets to unlock 10 to unlock a tier

epic 15 packets to unlock 25 per tier

legendary 50 to unlock and 50 per tier

mythical 75 to unlock 100 per tier

insta plants like cherry bomb potato mine squash etc don’t have tiers