Dedede seems like a good character to plant C4 on too since he won't die to anything. Can you transfer the C4 by grabbing someone? If so, planting C4 on a Dedede, chaingrabbing to the edge, and then using fthrow->bair->C4 explosion could be really good. If not, you could just try to touch them some other way, suck them up, and blow them away (that sounded a lot less dirty in my head).
Seibrik and G-reg did really well with Dedede/Snake at C3 also. I was really unsure about it since it seems like they'd have trouble against faster teams that included some combination of G&W, Falco, MK, and Pikachu, but if I'm not seeing many of them it would definitely be something to consider. I AM technically a Dedede main after all.
To be honest, my partner and I have never really discussed doubles strategy in-depth. When we decided to go MK/Snake it was before I picked up G&W, so I don't know if G&W/Snake would be better or not. Then there's also his Toon Link to consider. We basically have 6 possible combinations that could be viable, all of which are roughly equal. So many decisions...