To convert from M4 or V4, you need M4
for Genesis 2.
There is a huge amount of clothing content for Michael 4 and Victoria 4. Some of it is by really outstanding artists who do not or have only recently worked with G1 or G2, and some is quality work that was never updated but is available cheaply, including many of DAZ's Platinum Club items. You can take best advantage of this by using Transfer Utility in addition to AutoFit. This tutorial will show you how to use Transfer Utility to preserve skirt handles, fancy sleeve rigging, or basically any extra bones that are normally lost in the conversion process. I've done a different tutorial
for converting custom bone items between G1 and G2 already and a post on converting high heels to G2
I posted this in the thread for the Sickle Rigging and Morphing System over on the DAZ forums, but vwrangler
pointed out there are some advantages to having it here as well, so that people can favorite and archive it more easily. Also, you don't really need SRMS (or G2 Basic Rigs from my store) to do this; since this method lets us keep skirt handles, no template should be necessary at all. It just can provide a smoother conversion in some cases, and some of you already have it, so I will include that option in the directions.
You absolutely do need to have DAZ Studio 4.6 or later. DAZ Studio 4.6 contains the update that allows weight maps to overlap at values higher than 100%, and that's very necessary when keeping Generation 4 handles.
Load a Gen 4 or other item. Load Genesis 1 or one of the Genesis 2 figures. Do not apply morphs, scaling, or poses to the figure. If you try to use this to quickie-fit an outfit to your posed and morphed characters it probably won't work.
In Scene Tab, go to edit—rigging—convert figure to weight mapping. Choose TriAx.
Start the Transfer Utility. Its icon looks like an arrow pointing up and to the right. As "Source" choose the figure. As "Target" choose the clothing item. Also choose Clone or Morph V4 on the left dropdown under Source. You may need to experiment with what works best on the individual item, but for me it usually it needs to be Clone V4 if there are long sleeves whereas Morph V4 sometimes gives better skirt results.
Choose template—SRMS bodysuit or dress or boots as appropriate, or Basic Dress/Basic Tunic if using G2. Otherwise using no template may be best. I definitely recommend that on items with fused pants and boots.
Uncheck everything but Morphs and Reverse Source Shape from Target in the advanced options below. Add a smoothing modifier. Do not check Fit to Source Figure. Uncheck it if it is checked. Vwrangler reports that leaving this checked may result in bad results on superposing items like the Amazing Braid from Renderosity.
Let it run. It may ball up when it’s done. If so, don't panic.
Select G1/G2 and then the item with ctrl+click in Scene Tab (in this order). Click on the tiny icon that looks like three lines and a triangle to the upper right of this. Activate Edit—Rigging—Transfer Rigging (Figure Space). Now it should be fitted to G1/G2 properly but still have its extra bones.
Save the clothing item to library and reload. Do not move or morph G1/G2 before you do so.
I've seen others on the forum reporting incorrectly on the use of Wearables presets. Don't save as these. The purpose of Wearables presets is to save a loader that can load many preexisting items at once, not an individual item that doesn't exist in the library yet. Instead, use File--Save As--Figure/Prop Asset, and fill out the form accordingly. Try not to use the exact name of the product in case it is later converted by the original artist and you might want both versions.
In my testing, this method has been effective, although one still has to add a push modifier sometimes (found in that same edit dialogue as the transfer rigging option). There's no helping bad or unfused geometry, so watch for sellers who seem to do that regularly and don't plan on buying their content for conversion use. When in doubt, buy their cheapest thing that is still recent, test it, and see if it performs, has been my policy. I can't list everyone who makes conversion-friendly products, but here are those I can attest to personally:
-DAZ3D vendors and legacy content, basically across the board but definitely Daz Originals/Platinum Club
-Xurge3d (One or two bodysuits have mesh gapping, but usually if you update the mats to use his displacement it's not visible)
-Alfaseed/Aerysoul (About everything I tried, lots of very dense, fused geometry so very good candidates)
-Val3dArt (Kyrie, at least)
-PowerAge is not 100%, but recent work is good. I have a freebie sweater of his with split geometry that comes out dreadfully, but the BlackMoon and his shiny armors converted well.
-I haven't tested OutOfTouch's earlier stuff, but more recent pieces are very sound geometry and he even makes things for G2 now (hooray).
-I don't have LadyLittleFox's things but have heard mostly positive things about their convertibility.
I will be happy to add to this list if you have others to suggest whose work you are certain converts well or poorly based on its geometry.