At the beginning it can be scary to try the Lawyers. But practice with Old McDonnell a few times and you'll probably be confident enough to invade. When you start, you'll face two types of ten lawyers. The lawyers are very tough and can hit pretty hard, but they shouldn't be too hard to handle with a tough army. At this level and above, the Green Zombies are essentially useless. The regular lawyers should be quickly demolished after sending the majority of your zombies. Still blue or even red are highly recommended. The trick to beat those lawyers is healers. The lawyers' boss throws at a somewhat slow rate (1 item / 5 sec) which makes it very interesting for garden types. After defeating the lawyers, the boss will come down, but he is much stronger than he looked on the second floor, dealing high damage and sometimes pushing and stunning your zombies. If you have a good combination of large, tough and fertilizer zombies you should defeat the boss easily and not lose any zombies. Once you unlock all level 2 abilities, he will be a piece of cake. Use 1 kindlehead 3 zombruisers 3 zomgoblin 2 zombotanist 1 amazombie and 6 zyborg. with kindlehead first and the rest in any order you want.
How to beat Laywers with Blue Zombies
At level 21 the laywers can be beaten with no losses using this combination of blue zombies. 3 kindlehead, 6 zombeauty, 5 zombruiser 1 zyborg & a zombotanist. They all had mutations but were not all fully mutated. I sent them in: kindle, beauty, bruiser, zyborg, botanist & than alternated the rest until finished. When I first attacked the lawyers I had about 5 green zombies (good mutations) with the rest my first harvest of blues, just beacuse I wanted to try it. We won but I lost 4 of my green zombies so I naturally replanted blue ones. The lawyers get easier & easier to beat because at around level 21 you start to earn abilities these do start to make you zombies just that bit tougher. Do be careful of attacking too soon, because if you get clever and go in not fully hungry then it will be much harder to win. Of course by the time you have red & combination zombies you will have very few problems no matter how you attack.