Those are all REALLY valid points and definitely something worth exploring. I don't really have anyone else though to fill in for an offensive team myself.
Look at who you have available 1st & what powers they have at what cost. When I play, yes, I want to make that rainbow team, but in playing against the computer I just picked up on some things I noticed. Computer is low cost and cheap, always goes for easy matches & always seems to target your special tiles.
If you want to hit fast & hard, here's what I suggest from what I know.
Psylocke- 6 black AP, decent damage leaves attack tile.
Ares- At level 5, 5 green AP decent/high attack but will give opponent green AP
Classic Magneto- Red at Level 5 only costs 2 AP, low attack but low costs
Astonishing Wolverine- 6 green AP low attack strike tile generation
Modern Storm- At level 5 Red only costs 5 AP, low damage but great for cascades & gain of environmental tiles (USE ONLY IN DESERT OR JUNGLE STAGE!!!!)
Ragnarok- 6 Red AP, produces green tiles, low attack
Those are the only ones I really know or use that can attack in 2 motches, in Magnetos case 1. Its an interesting theory for sure, I definitely one that needs to be explored
*Note*
I did not include Loki's purple. Although low cost, the percentage of times it will make a match or high damage cascade are VERY low.
Did not include Human Torch, covers are few and far between for him to be effective unless you directly bought powers. Green attack costs low AP, but still requires 1 green AP per turn. If you have no green AP the green countdown tile will not attack.
If anyone notices anything I missed just let me know!