Just posting to put out some ideas for a Garchomp replacement.
Tangrowth - One of the bulkiest pokemon around it could be run as a supporter, or a sun sweeper. Regenerator and Chlorophyll make it a good team player. Slowest Sun Sweeper, but it is bulky like Garchomp and has good mixed attacking stats, along with an amazing support movepool.
Venusaur - Perhaps the best Sun sweeper of Gen V. Can wreck entire teams by itself after a Growth. Relatively bulky, which means that it won't be put down by priority after it starts sweeping. Poison typing gives it a resist to fighting types, and allows it to absorb Toxic Spikes. I find a special set to be the best for me.
Rhydon/Rhyperior - As bulky grounds go these are the best (In my opinion). Under the sun their water weakness is much more manageable, and with your team Grass pokemon are no problem. As such these can again take the place of bulky sweeper, or physical tank. Rhydon takes Nuetral hits like a boss, and with 130 base attack he can hit back hard. Rhyperior on the other hand has a little bit higher attack and can carry leftovers/life orb/whatever. I have used both on sun teams and they perform well, being great checks to Sand. They do have those nasty 4X weaknesses, but as said Sun nueters water (Which your team handles well enough anyway) and the rest of your team have nothing to fear from grass.
These are just some thoughts on what could be used now that Garchomp is gone. All of them have their pros and cons, but for your team they seem to synergize nicely. I based my suggestions around what you seemed to be using Garchomp for, which was to take physical hits and then punch holes in the enemies team.