I'm thinking of doing an entire team of wheel chair combatants. 300 points

my options that I have or soon will have

Hector Hammond JL
Oracle Legacy
Professor X M&M
Chief Crisis

what kind of feats should I use?
what kind of strategy should be used?

If you want a bigger point team that's true to your theme, throw Wizard Shazam in there. But his chair doesn't have wheels...

Or AW Magneto...

Feats? A couple of Mental Shields or Protected coudn't do harm.
Strategy: Run like hell. Chuck is going to be your primary offensive tool (I would go for Xavier LE if you have him) so chuck Chuck out and try to cover him up with Oracle afterwards. Again... mobility will be your handicap so good luck with that.

I'd consider using the Alpha Oracle instead of the Legacy one. A much better attack value, defense value, damage value, ranged attack, and Mind Control, which can be used in conjunction with Professor X.

Also, I'll agree with TheLord -- if you have access to LE Charles Xavier, use him. He's much more offensively minded, and unfortunately most of the figures you're using won't share a keyword with Professor X, so you won't as much use out of his Cerebro power. I would definitely recommend the LE (and he's cheaper, too).

Know what?

New SI Doc. Strange could be the ultimate weapon in a team like that, he can give you a good defense boost when he is on is first click (if you can't avoid to get targeted by enemy fire, then try to dodge as many bullets as you can), and he can also blast the enemy when his chaired comrades would normally block his view.

Actually the only problem is that he dont have a chair with two pair of wheels, but you can always say that it can't be a real problem for the sorceror supreme to create some.