His team definitely has great team synergy. She Hulk backed up by Shopping Cart is EXTREMELY GOOD as if they block it, they have to deal with She Hulk's mix up vortex. Any grab allows Combo to probably raw tag into either Frank or Spencer for a TOD or level up. Anti air grapple assist allows for grab shenanigans or raw tag crumple stuff too or mix ups on incoming character. Frank with She Hulk and Spencer assist is also legit as he gets unblockables, combo extensions and mix ups against in coming characters. Spencer also does well with both assists combo and mix up/lock down wise.
The problem is that in any configuration, he has to actually get in to utilize any tech. It's a team that will struggle against zoning but once in can lay a serious hurt on them. Also double slides and double anti air grab hypers. Combofiend seems to love those.
synergy and ability are two very different things. you can roll low tier all you want, as long as you put in the basic things a team needs to compete.
like lets take kusoru's team.
Point character that can zone or rushdown (Joe)
Second character that provides a great assist and a good safe DHC (shopping cart super)
Anchor with a great assist and strong xf3
Kusuro has the most important ones I guess: safe DHC out for point character, great neutral assist (shopping cart), great anti-air/zoning assist (log trap)
Then after that he has all the other things: absolutely amazing incoming mixups, anti-phoenix tech, xf3 anchors, ways to chip, ways to team with morrigan etc. etc. etc.
Combofiend's team, aside from having stuff combofiend likes, goes to shit the same way that Noel Brown's does: Frank has nothing to help him get in and do anything and he ends with Dark Spencer and Lvl 1 Frank.