Sometimes I base defend with wolverines/cobras in 3 vs 3 to rack up points. Here are some tips on when to and how to
1.If the opposing team has a covenant player, forget about it. Hunters>defense
2.If the opposing team has a cutter player, forget about it. ODST spam behind your base and the patch upgraded their rpg damage. If there is 1 cutter on the team, it's up to you. You can throw a few flamers in there but the odst spam will overwhelm the flamers. 2 cutters, don't defend and just attack.
3.Best maps to defend is fort deen and frozen vally. Exile is not that great due to the fact their are 2 reactors and an early rush can ruin your defense.
4.Best person to do base defense is anders. Your first base should have all supply pads and 1 reactor. Take a second base with hogs (3 is enough) and start building your army there.
5.After a while, they will go infantry. Make sure you have a barracks in your base and pump out flamers as cobras/wolverines die. Once the threat is finish, sent the flamers to their base so they can die and so you can replace them with new cobras/wolverines.