Power-up often. Nothing is worse than running out of energy while pummeling your opponent. And if you wear yourself out it is likely you won't recover until it's too little, too late.
Avoid characters with little energy and attack power. A lot of characters must charge up constantly due to their constantly getting exhausted. The bad part is that sometimes you wear out so fast your fighter doesn't do very much damage.
Fight Flared. When you flare up, your energy will drain. However, many characters can fight longer while flared than not, plus it adds strength to your attacks for most fighters. The rate of power usage doesn't go up even when attacking, so damage depends more on how fast you are rather than how many times you attack, hit or miss.
Put up Your Dukes. In a 1-on-1 situation, keep your guard up. You will be able to time your opponent's attacks and you can usually get them while they leave themselves open. Plus you will also wear down your opponents energy, forcing him to power-up; an ideal time to lay it on 'em.
Stay Inside. If you make a pattern of hitting your opponent, moving up to him, hitting him again, and repeat, your challenger will try to flare up and fly away a short distance to power up. Just stick to your pattern, and all the flaring up will exhaust your opponent, leaving him a sitting duck. Remember that even when you seem to be low on energy, your opponent will use up more than you and will probably wear out faster. But you can charge up for a split second after each attack (Just make sure you let go of the power-up button first or you could end up in deep stool).

Beating the Computer- The easy way (Story Mode)

The best strategy here is always to throw in your 3 toughest fighters. Whenever your team leader gets so low on life that another Meteo could kill him, just switch him with your next fighter, keeping him protected and making a healthy fighter take the damage. If you feel like you are hurting your team more than helping, you can go to the character select screen and let the computer fight for you...Just keep an eye on the power balance. If you think that one of your fighters is doing some poor fighting, get him out immediately and replace him with another; although some characters are better than others, the computer controls each one differently, making the appearance that some fighters have more experience than others.

Beating the Computer- The easy way (VS Mode)

The strategy here is very much the same as above, with a few exceptions. The first is that you can't go into a character select screen, meaning you can't substitute fighters or make the computer control your character for you. The second is that you will need a new strategy to fight a 1-on-2 fight, where your 1 fighter is forced to take on 2 baddies. The first thing you should remember to do is NEVER STOP MOVING. Keep in a constant backpeddle, and when your opponents close in on you, flare up and go full speed ahead to your targeted enemy. When the opponents flare up to chase you, they must stop to power up often. Once you get the timing right you can attack your target without his sidekick getting in the way due to the fact that when the computer recharges, it does so until his energy is completely restored. That means you have a bit of time to give your target a good what-for. When the other adversary shows up, rocket out of there before he can do anything to hurt you. If you repeat this successfully 2-4 times, you should be able to get in a meteo. Keep it up, and you should narrow down the odds to even. If you get into a 1-on-3, use the same method. You just won't have as much time for each attack, meaning it could take several attacks to get off a meteo. That's why you should never fight with Guldo! Oh, all that back-tracking could get you cornered. If that happens to you, you must act, and do it FAST. Move forward a little to get yourself away from the boundary, then charge up and double-tap to either left or right to turn your flight angle, giving you more room to run.

Beating the Computer- The easy way (SP mode)

SP mode places you into a series of 30 battles, ranging in fights of 1-on-1 to 3-on-3 and most everywhere in-between. Use the methods listed above, depending on what kind of fight you are currently in.

I'll probably be adding to this soon. Keep that Reload button handy if you use Netscape!