You will lose all coins you earned to the point you change the sides.
Most of the plants are skilless variants, some are still broken, overpowered, with high area dmg and easy spam, so they are popular. A chomper beginner is most likely a suicide chomper: Goop + Burrow = easy kill + you go down or survive with 10 health, Rose with spam abilities, high xp reward due to the teleport, immortal for 10 seconds and autoaimspam makes her the perfect newbie class, corn has 25 more health then the foot soldier, 3 insta kill attacks, hight accuarcy and a lot of ammo, citron, even with nerf completly broken on top an experienced electrocitron can 1vs1 anyone in all distances, peashooter, mostly electropea is (when you know the trigger) the most broken and strongest electrovartiant in the game, sunflowers, except fire and vampire, are only played to get levels, cacti is also rarely used.
The second thing is that you earn more coins with plants then zombies, the opposide to GW1 where the zombies got more money. Zombies lose 75% of all matches I played in almost 1000 hours of gameplay. Plants win 99% the map Waste of Time Seeds of time, in GWN it stops at the second or third garden, they win every second match on zombopolis and almost any zomburbia match comes to the endgame, but its hard so zombies will win that map mostly, on moonbase the plants also win almost any time, since captn sharkbite, parkranger and electro brainz got nerfed and that is months ago! Still a lot of players just go solo killing and arent focused to capture the target, staying behind or camping, the result is that it ends on the first or second garden.