First off, if you'r tempted to do this in co-op play you actually may want to do it solo. I actually found it much harder to do co-op. It seems harder to focus on positioning and enemy movements with two people on screen and I tend to play worse (more spammy and focusing on trying to rack up combos). I tried a few times with someone else but in the end I did it solo (took many attempts!). Also with co-op you have to worry about lag and disconnects (one time it happened on stage 6....total bummer).
Few tips for solo arcade play: Dont worry so much about combos. You want to survive and while you need points for extra lives you can't earn points if you're dead. Focus on staying alive and then hit those combos when the opportunities present themselves. Dont combo hunt. Also I found throws were super helpful as a crowd control mechanism and to get some iframes. If you have an enemy clinched from the front and an enemy is behind them and you know they are going to close in and attack wait until they are about to make contact and then vault over your enemy. As you jump to their back you are invulnerable.
I found my best success came with SOR1 Axel/Blaze btw. Pared down mechanics means positioning and fundamentals were the focus and their jab is rangey, powerful and can stun multiple people at once. Also Axel can knock back multiple enemies in a line with his clinch headbutt .
I'm nothing special at this game so if I was able to do this you can too. Just brace yourself for the possibility of having to try again.....and again......and again.....
Good luck!