>>529852219
The Deadly Six are literally the only other worthwhile recurring villains that aren't killed in their introductory game or god kaiju. Mephiles and Infinite are fucked over by circumstance, Black Doom is a Shadow villain, and they have no idea what to do with Eggman Nega.

It's a good thing to me, but it really highlights how one-off they've treated Sonic's rouges. In a way you can argue it mirrors Sonic's own philosophy of fixing a problem and moving on to the next, but it doesn't really help the series in the long run.