The only really good coordination I see with regards tanks is the flame rush. This tactic can be countered as it is, the key is really speed and surprise. Even then you get people stoping to repair, attacking the harvester or chasing after tanks who are probably already reporting to their team "FLAME INC!"On field most people will camp outside even if they are losing by points. When this happens it only takes a few Railgun shots to rack up more points for Nod. The tanks don't usually last long either, if they manage to get past the artillery.
One tank will not destroy a protected base regardless of the player!
Oh and another thing, please dont repair your tank on the field! Its usually crawling with stealth black hand