There is no way to counter an earthbender that knows what he's doing. The closest thing to a counter is an airbender who knows how to dodge and fight at range. Water can lure earth into water or use torrentsuction. Fire usually works by catching them on fire, and staying back. Earthbenders can tank anything from blaze to walloffire with eartharmor. But you can firejet into charged fireblast them. This counters raiseearth spammers. Get em from behind !
And earth vs earth is all about landing hits from under, or near them. Side shots are also an option. Most importantly, if you use eartharmor after an opponent, their eartharmor wears off before yours. You can tank their shots at half damage, while you do full damage.
If you don't care about being cheap, if you spam airsuction and get an earthbender into water, its over.
BUT, if an earthbender is good enough, they are almost invincible at times.