PvZ 3 idea to remove plant/and zombie leveling

As I mentioned before I think both plants and zombies having levels is not good for this level because if tier 1 plants are higher level than there is no need to merge plants which ruins the entire point and zombie levelling just turns the game way too Grindy 

so an idea is to both remove plant leveling and to buff the merged to make players more encouraged some examples are

Slaw slinger: cabbages burst into shrapnel dealing damage to zombies in a 3x3 area around the target

Cab barrage: first cabbage spits into 2 dealing  damage to zombies next door

Repeater: every 10 shots shoots an additional pea 

Gatling pea: every 45 seconds ranks up

Rank 1 shoots 4 peas Rank 2 shoots 5 peas Rank 3 shoots 5 peas and 1 pea in lanes next door

and how to fix zombie levelling  is for make more zombies spawn overtime also make some zombies resistant to specific plant types so you don’t use the same few plants every level