Everybody is extremely over-powered in Kid Icarus: Uprising. Therefore, I need some ideas on how to be on the same level of strength as them. Can anyone give me ideas on how to do that?
You'll want to have weapons that specialize in melee attacks and weapons that specialize in ranged attacks. For both types of weapons, you'll want as high of a rating for its given damage type as possible (6 stars if possible); don't worry about the other damage type. overall defense and health modifiers are always very helpful too. Remember that higher value weapons are not always more useful, and enemies will get more points for killing you when you have a higher value weapon, so you want to balance power and value.
For ranged weapons, most players prefer staffs. Staffs and clubs are good choices for sniping, while palms, orbitars, and bows are good choices if you want high homing ability.
Charged shot and continuous fire modifiers are great for ranged weapons. Full-health boosts can be good if you plan to shoot from afar. Shot homing and shot cancellation are extremely helpful, but remember that shot homing modifiers won't help weapons that have no inherent homing ability.
For melee weapons, most players choose claws. Claws are great for melee because they hit faster than any other weapon type, and also give you a speed boost. Arms and clubs can be good for dealing a lot of damage in a short time, but won't give you the speed boost and constant hits that claws will.
Obviously, you'll want melee combo +4 and melee dash attack +4 modifiers. Other especially useful modifiers include freezing, petrification, stamina, and speed bonuses.
See Icarus Wiki's weapons pages for individual weapons. There's a lot of useful information there for deciding which weapon you want to use, but it's not complete.
As for powers, you'll want to pick ones that work well with your weapon, but also ones that you like playing. I personally love destructive powers such as Mega Laser or Explosive Flame.
For ranged weapons, Homing Boost, Quick Charge, and Slip Shot are very useful. If you're using a club for ranged attacks you should try Invisible Shots too, so your enemies don't see your shots coming.
For melee weapons, Black Hole is great for holding your enemies in place while you wail on them, as are Paralyze Attack and Petrify Attack. Interference, Darkness, and Transparency can help you sneak up on them without being seen. Tirelessness is invaluable when it comes to engaging and disengaging combat. Playing Dead is especially fun to use when fighting another melee player.