9+12+16+24+42= 103 dmg
11+15+20+30+52= 128 dmg w/ Power2 buff
Jean's unlucky to have a single-target Attack Combo (doesn't use hitbox) in a game with mobs of enemies clumped together. Fortunately her aspd is much better than Emma Frost's making it a lot less unbearable and the range/limited targeting makes it perfect in Boss fights.
37 dmg, Dance Effect
Surprisingly useful against priority targets, the 37 dmg is already decent for 1 Star but the best part is that the Dance Effect lasts much longer than Stun and other immobilizing status effects.
For example, It works wonders on Mystique when she transforms into other characters effectively putting her on lockdown for your teammates to get free hits in. Other situations may include Dr. Doom's clone summons and Psylocke/Iron Patriot "Ghosts" in Onslaught.
30 dmg, AoE, Self-Buff, Knockback
The framerates required for this skill makes this unreliable as a DPS Power but despite the framerate problem it's still very handy for a character like Jean (Single-target Attack Combo) against groups of enemies as a low-cost AoE option. The "Slowing" effect is close to unnoticeable making it somewhat of a disappointment as a status inflicting Power.
Special note, before this Power becomes a "Super Power" when the character reaches level 8 it is also a Self-Buff that increases the dmg of all her attacks! It's beyond me why this effect disappears after the Power levels up, may be a glitch on Gazillion's part but it makes her a much weaker character in general.
70 dmg, Knockback
A fairly straight forward Single-target damaging Power, framerates are a bit longer than one would like it to be but it has enough range for it to be relatively safe in Boss fights. I wouldn't recommend it on anything other than Bosses, especially if you could just use Power1 and make them dance for 37 dmg at a third of the cost.
66 dmg, AoE, Knockback; continuous 3+3+3 dmg on touch.
Although the dmg isn't very high for a Hero-Up it's more than adequate to help clear a room if the time calls for it. The after-effect also lingers quite awhile so if a team needs the knockback support go ahead and run through the crowd. Otherwise stay back, since flinging enemies up in the air does diminish overall DPS by FCing your teammates Attack Combos.
How to Play:
Just stay back and provide overall ranged DPS for your team, since she has a Single-Target Attack Combo, try to prioritize the enemies you choose to take out first. You will have the option of using her Power2 frequently to AoE groups of enemies or simply save up for her Hero-Up. Either way you won't be able to deal much damage, that being said it should be no problem for you to find stronger enemies to immobilize with Power1 in a mob, it will be the best way you could assist your team; you may choose to Power3 instead of Power1 for the kill but with her limited SB I'd recommend playing more conservatively so you can Hero-Up as much as possible.
Jean excels more in Boss fights, keep yourself buffed as much as possible and simply DPS from afar and use Power3 whenever you can for even more dmg. In most Boss scenarios your range allows you to deal more damage than anyone else on your team (less dodging required) so try to get as many hits in. (Unless of course it's a special case like Mystique where your Power1 makes her a harmless dancer when she transforms into another character)
She's has no real good DPS options and an underwhelming Single-Target Attack Combo. However, her Attack Combo's range and Power3 raises her usefulness dramatically against Bosses. Fortunately, her usefulness also increases in situations where immobilizing/slowing priority targets are incredibly important since the dance effect lasts quite a long time. If SHSO releases more Bosses like Mystique or powerful enemies that are susceptible to such Powers she'd be more valuable.