Give me a exactly three (1) minute to spit this knowledge....
Earth main is by far one of the most useful main out of the 5 although he may seem pretty useless due to this artilery but be not foolish as the crimson man (earth main) is the best ideal main to use to develop the skill which goes by the name of "D.I.R" or "Doing it right".
The Earth main has loads of choices varying from defensive, offensive or mix though mix takes devotion to understand how the mix is needed.
If we to put the mains to fight among theirselves in a 1vs1 I would give the crimson man 3rd place, this is because as of the recent changes and development he has the ability to change his artillery through battle from shield to a ninjutsu, this allows the earth main to stack shields and deal damage. But in a team the earth main is quite the beast!!

Not to be a thorn in your side but I'll just put some sauce in the mix but you don't need to spend money to be a successful earth main just grind and pick your choices correctly.