I am stuck agianst rayquaza please tell me what to improve THIS IS NOT..

Well squirty knows ice beam which should be super effective, level your poke a bit higher or you could cheat to level up.

Lol you should be fine your just coming at Rayquaza the wrong way. Try this method. When you start the battle, use Ice Beam to attack Rayquaza from a distance.

Then when he's in front of you, use protect which lasts a few turns so his attacks are halted. After his attack fails because of protect, turn off all moves on chikorita except for attract.

After he's done using attract turn his other moves back on. If protect wears of just use it again and then use ice beam to keep hurting rayquaza until he dies!

Hello.
Since your squirtle has protect, I suggest you use it against Rayquaza. Same with your Chikorita's attract. Another thing is, when you enter the floor that Rayquaza is on, use Ice Beam right away since it attacks in a straight line and Rayquaza is weak against ice attacks.

Your question about SOS mail:
When you die, say yes when it asks if you want to send a distress call. It will save your game and send you to the main menu. After that, go to "Friend Rescue" and select "Get Help". It will ask you if you want to do it "wirelessly" or "password." Pick "password" and it will show you an SOS password. Use that password and post it on the:

SuperCheats Pokemon Mystery Dungeon Blue Rescue Team Forums

Then someone should save you. Keep in mind:
Be patient because it may take a while.

Once the you have been rescued, the rescuer should then post an A-OK mail password, which you type into "Friend Rescue-->Get Help--> Recieve A-OK mail." Once that's done, you will be revived with your money and items so you can continue.

Don't forget to send them a thank you mail!!!

Hope I helped!!!

Hi thanks for your help however I don't have enoth PP when I go up agiast him also when I beat rayquaza will I be able to chosse a different leader evry time I want a diff one?

Have Chikorita use attracct to distract rayquaza and then have squirtle use ice beam.Since Rayquaza is dragon type it will be super effective.just keep haveing chikorita use attract and squirtle use ice beam and you be able to kill rayquaza pretty easily.

If you come across airidactle have squirtle use waterfall, it's super effective.

Get there levels up.

The others gave good suggestions, follow them! USE ICE BEAM!!!
This is to your second question:
If you don't have enough PP when you get to Rayquazza, then bring Max Elixirs-save at least one for right before you reach him!! Also, use regular attacks or items like sticks and gravelrocks when you can to save the real moves for harder foes.
And, yes, after you beat Ray you'll be able to switch leaders to any other Pokemon you have or do recruit, and add whomever within the size limits to your team if any at all, and you can evolve them, too, finally!
Hope this helps!!