99 Pokeball
28C6AC82 00000063

99 Master Ball
28C6B5F2 00000063

99 Great Ball
28C6B5F6 00000063

99 Safari Ball
28C6B5FA 00000063

99 Dive Ball
28C6B5FE 00000063

99 Repeat Ball
28C6B602 00000063

99 Luxury Ball
28C6B606 00000063

99 Dusk Ball
28C6B60A 00000063

99 Quick Ball
28C6B60E 00000063

99 Potion
28C6B612 00000063

99 Burn Heal
28C6B616 00000063

99 Awakening
28C6B61A 00000063

99 Full Restore
28C6B61E 00000063

99 Hyper Potion
28C6B622 00000063

99 Full Heal
28C6B626 00000063

99 Max Revive
28C6B62A 00000063

99 Sodaa Pop
28C6B62E 00000063

99 Moomoo Milk
28C6B632 00000063

08C6F2C8 000102D6

You can only use this code in Petalburg Woods!

After using the code, press R and Start to get 721 Master Balls and 100 Ultra Balls. Depending on how many Master Balls and Ultra Balls you have left in your inventory, you will encounter a different Pokemon.

For example, if you throw all Master Balls but only keep 1, then that will correspond to the Pokemon that is #001 in the PokeDex.

It works similarly with the Ultra Balls, but this decides the level of the Pokemon. If you have 50 Ultra Balls left, then the next encounter will be level 50.

Last step is to press and hold down L while walking and looking for a Wild Encounter.

The full PokeDex index is pasted below the code:

D3000000 00000000
DD000000 00000108
18C6AC80 00000001
18C6AC82 000002D1
18C6AC84 00000002
18C6AC86 00000064
D0000000 00000000
DD000000 00000200
D3000000 00000000
DA000000 08C6AC82
C0000000 0000003D
D7000000 08D0905A
DC000000 00000002
D1000000 00000000
D0000000 00000000
D3000000 00000000
DB000000 08C6AC86
C0000000 0000003D
D8000000 08D0905C
D8000000 08D0905C
DC000000 00000002
D1000000 00000000
D0000000 00000000
D3000000 00000000
D0000000 00000000

Here's the PokeDex list:

Treecko  
#001  

Grovyle  
#002  

Sceptile  
#003  

Torchic  
#004  

Combusken  
#005  

Blaziken  
#006  

Mudkip  
#007  

Marshtomp  
#008  

Swampert  
#009  

Poochyena  
#010  

Mightyena  
#011  

Zigzagoon  
#012  

Linoone  
#013  

Wurmple  
#014  

Silcoon  
#015  

Beautifly  
#016  

Cascoon  
#017  

Dustox  
#018  

Lotad  
#019  

Lombre  
#020  

Ludicolo  
#021  

Seedot  
#022  

Nuzleaf  
#023  

Shiftry  
#024  

Taillow  
#025  

Swellow  
#026  

Wingull  
#027  

Pelipper  
#028  

Ralts  
#029  

Kirlia  
#030  

Gardevoir  
#031  

Gallade  
#032  

Surskit  
#033  

Masquerain  
#034  

Shroomish  
#035  

Breloom  
#036  

Slakoth  
#037  

Vigoroth  
#038  

Slaking  
#039  

Abra  
#040  

Kadabra  
#041  

Alakazam  
#042  

Nincada  
#043  

Ninjask  
#044  

Shedinja  
#045  

Whismur  
#046  

Loudred  
#047  

Exploud  
#048  

Makuhita  
#049  

Hariyama  
#050  

Goldeen  
#051  

Seaking  
#052  

Magikarp  
#053  

Gyarados  
#054  

Azurill  
#055  

Marill  
#056  

Azumarill  
#057  

Geodude  
#058  

Graveler  
#059  

Golem  
#060  

Nosepass  
#061  

Probopass  
#062  

Skitty  
#063  

Delcatty  
#064  

Zubat  
#065  

Golbat  
#066  

Crobat  
#067  

Tentacool  
#068  

Tentacruel  
#069  

Sableye  
#070  

Mawile  
#071  

Aron  
#072  

Lairon  
#073  

Aggron  
#074  

Machop  
#075  

Machoke  
#076  

Machamp  
#077  

Meditite  
#078  

Medicham  
#079  

Electrike  
#080  

Manectric  
#081  

Plusle  
#082  

Minun  
#083  

Magnemite  
#084  

Magneton  
#085  

Magnezone  
#086  

Voltorb  
#087  

Electrode  
#088  

Volbeat  
#089  

Illumise  
#090  

Oddish  
#091  

Gloom  
#092  

Vileplume  
#093  

Bellossom  
#094  

Doduo  
#095  

Dodrio  
#096  

Budew  
#097  

Roselia  
#098  

Roserade  
#099  

Gulpin  
#100  

Swalot  
#101  

Carvanha  
#102  

Sharpedo  
#103  

Wailmer  
#104  

Wailord  
#105  

Numel  
#106  

Camerupt  
#107  

Slugma  
#108  

Magcargo  
#109  

Torkoal  
#110  

Grimer  
#111  

Muk  
#112  

Koffing  
#113  

Weezing  
#114  

Spoink  
#115  

Grumpig  
#116  

Sandshrew  
#117  

Sandslash  
#118  

Spinda  
#119  

Skarmory  
#120  

Trapinch  
#121  

Vibrava  
#122  

Flygon  
#123  

Cacnea  
#124  

Cacturne  
#125  

Swablu  
#126  

Altaria  
#127  

Zangoose  
#128  

Seviper  
#129  

Lunatone  
#130  

Solrock  
#131  

Barboach  
#132  

Whiscash  
#133  

Corphish  
#134  

Crawdaunt  
#135  

Baltoy  
#136  

Claydol  
#137  

Lileep  
#138  

Cradily  
#139  

Anorith  
#140  

Armaldo  
#141  

Igglybuff  
#142  

Jigglypuff  
#143  

Wigglytuff  
#144  

Feebas  
#145  

Milotic  
#146  

Castform  
#147  

Staryu  
#148  

Starmie  
#149  

Kecleon  
#150  

Shuppet  
#151  

Banette  
#152  

Duskull  
#153  

Dusclops  
#154  

Dusknoir  
#155  

Tropius  
#156  

Chingling  
#157  

Chimecho  
#158  

Absol  
#159  

Vulpix  
#160  

Ninetales  
#161  

Pichu  
#162  

Pikachu  
#163  

Raichu  
#164  

Psyduck  
#165  

Golduck  
#166  

Wynaut  
#167  

Wobbuffet  
#168  

Natu  
#169  

Xatu  
#170  

Girafarig  
#171  

Phanpy  
#172  

Donphan  
#173  

Pinsir  
#174  

Heracross  
#175  

Rhyhorn  
#176  

Rhydon  
#177  

Rhyperior  
#178  

Snorunt  
#179  

Glalie  
#180  

Froslass  
#181  

Spheal  
#182  

Sealeo  
#183  

Walrein  
#184  

Clamperl  
#185  

Huntail  
#186  

Gorebyss  
#187  

Relicanth  
#188  

Corsola  
#189  

Chinchou  
#190  

Lanturn  
#191  

Luvdisc  
#192  

Horsea  
#193  

Seadra  
#194  

Kingdra  
#195  

Bagon  
#196  

Shelgon  
#197  

Salamence  
#198  

Beldum  
#199  

Metang  
#200  

Metagross  
#201  

Regirock  
#202  

Regice  
#203  

Registeel  
#204  

Latias  
#205  

Latios  
#206  

Kyogre  
#207  

Groudon  
#208  

Rayquaza  
#209  

Jirachi  
#210  

Deoxys  
#211  

DD000000 00000800
481FB58C 08200000
481FB92C 08200000
B81FB58C 00000000
00000008 00200000
D3000000 00000000
B81FB590 00000000
00000008 00200000
D3000000 00000000
B81FB594 00000000
00000008 00200000
D3000000 00000000
B81FB598 00000000
00000008 00200000
D3000000 00000000
B81FB59C 00000000
00000008 00200000
D3000000 00000000
B81FB5A0 00000000
00000008 00200000
D3000000 00000000
B81FB92C 00000000
00000008 00200000
D3000000 00000000
B81FB930 00000000
00000008 00200000
D3000000 00000000
B81FB934 00000000
00000008 00200000
D3000000 00000000
B81FB938 00000000
00000008 00200000
D3000000 00000000
B81FB93C 00000000
00000008 00200000
D3000000 00000000
B81FB940 00000000
00000008 00200000
D3000000 00000000
D2000000 00000000

Then press Y. After the first battle all Pokemon involved will be level 100.

08C71DC0 000F423E

?

28C83D94 0000000A

Mach Bike
08C6E888 00000001

Acro Bike
08C6E888 00000002

Hover Board
08C6E888 00000003

Only works with version 1.4

DD000000 00000044
B81FB510 00000000
DC000000 000000B2
20000000 00000001
D3000000 00000000
D0000000 00000000

DD000000 00000108
D3000000 00000000
18C6EC70 00000001
18C6EC72 000002D1
18C6EC74 00000002
18C6EC76 00000064
D0000000 00000000
DD000000 00000200
D3000000 00000000
DA000000 08C6EC72
D7000000 082C6C92
D3000000 00000000
DA000000 08C6EC76
D7000000 082C6C96
D3000000 00000000
98C6EC78 00000004
282C6C98 00000001
D0000000 00000000
D3000000 00000000

Version 1.4 only

D3000000 00000000
003D8748 E3A00014
DD000000 00000200
003D8748 E3A00004
D0000000 00000000

Works only on version 1.4.

08C6F5E0 03E70017
08C6F5E4 03E7002C
08C6F5E8 03E70029
08C6F5EC 03E70032
08C6F5F0 03E70035
08C6F5F4 03E7002D
08C6F5F8 03E70030
08C6F5FC 03E70031
08C6F600 03E70034
08C6F604 03E7002E
08C6F608 03E7002F

68000178 00000000
B8000178 00000000
20000EDD 00000001
D2000000 00000000

00419A34 E3A04003
0041A2A4 E3A05003

Only works on Version 1.4

08C71DC0 0098967F

08C6F5FE 000003E7

DD000000 00000100
182C8AF2 00000097
182C8AF6 00000001

On Route 119, hold R to find Mew in your PokeNav.

x99
28C6EC72 00000063

x255
0821C5EA 000000FF
08251942 000000FF
08C6EC8A 000000FF

x999
0821C5EA 000003E7
08251942 000003E7
08C6EC8A 000003E7

DD000000 00000200
481FB58C 08200000
481FB92C 08200000
B81FB58C 00000000
C0000000 00000002
C0000000 00000004
DB000000 00000119
D8000000 00000118
D8000000 0000011D
DC000000 0000000C
D1000000 00000000
D3000000 00000000
B81FB92C 00000000
D1000000 00000000
D3000000 00000000
B81FB590 00000000
C0000000 00000002
C0000000 00000004
DB000000 00000119
D8000000 00000118
D8000000 0000011D
DC000000 0000000C
D1000000 00000000
D3000000 00000000
B81FB930 00000000
D1000000 00000000
D3000000 00000000
B81FB594 00000000
C0000000 00000002
C0000000 00000004
DB000000 00000119
D8000000 00000118
D8000000 0000011D
DC000000 0000000C
D1000000 00000000
D3000000 00000000
B81FB934 00000000
D1000000 00000000
D3000000 00000000
B81FB598 00000000
C0000000 00000002
C0000000 00000004
DB000000 00000119
D8000000 00000118
D8000000 0000011D
DC000000 0000000C
D1000000 00000000
D3000000 00000000
B81FB938 00000000
D1000000 00000000
D3000000 00000000
B81FB59C 00000000
C0000000 00000002
C0000000 00000004
DB000000 00000119
D8000000 00000118
D8000000 0000011D
DC000000 0000000C
D1000000 00000000
D3000000 00000000
B81FB93C 00000000
D1000000 00000000
D3000000 00000000
B81FB5A0 00000000
C0000000 00000002
C0000000 00000004
DB000000 00000119
D8000000 00000118
D8000000 0000011D
DC000000 0000000C
D1000000 00000000
D3000000 00000000
B81FB940 00000000
D1000000 00000000
D2000000 00000000

Then Press L.

08C6EC70 03E70001

18C6F975 00000101

08C690A0 00000002

481FB58C 08200000
481FB92C 08200000
B81FB58C 00000000
1000000E 000003E7
10000010 000003E7
D3000000 00000000
B81FB92C 00000000
1000000E 000003E7
10000010 000003E7
D2000000 00000000

08C650C0 00000102

481FB58C 08200000
481FB92C 08200000
B81FB58C 00000000
C0000000 00000002
C0000000 00000004
20000118 00000063
20000119 00000063
2000011E 00000063
2000011F 00000063
DC000000 0000000E
D1000000 00000000
D3000000 00000000
B81FB92C 00000000
D1000000 00000000
D2000000 00000000

D3000000 00000000
00579820 E1A01000
00579824 E12FFF1E
00579828 E1A06000
0057982C E12FFF1E
DD000000 00000100
00579820 E3A01000
00579824 E12FFF1E
00579828 E3A06000
0057982C E12FFF1E
D0000000 00000000
580BB414 E1A01000
080BB414 EBF83D01
D0000000 00000000
580B87F8 E1A06000
080B87F8 EBF8480A
D0000000 00000000

Then hold R while walking.

DD000000 00000100
481FB58C 08200000
481FB92C 08200000
B81FB58C 00000000
1000000E 000003E7
D3000000 00000000
B81FB590 00000000
1000000E 000003E7
D3000000 00000000
B81FB594 00000000
1000000E 000003E7
D3000000 00000000
B81FB598 00000000
1000000E 000003E7
D3000000 00000000
B81FB59C 00000000
1000000E 000003E7
D3000000 00000000
B81FB5A0 00000000
1000000E 000003E7
D3000000 00000000
B81FB92C 00000000
1000000E 000003E7
D3000000 00000000
B81FB930 00000000
1000000E 000003E7
D3000000 00000000
B81FB934 00000000
1000000E 000003E7
D3000000 00000000
B81FB938 00000000
1000000E 000003E7
D3000000 00000000
B81FB93C 00000000
1000000E 000003E7
D3000000 00000000
B81FB940 00000000
1000000E 000003E7
D2000000 00000000

Then press R.

D2000000 00000000
0037A144 00000000
DD000000 00000100
0037A144 3F800000
D0000000 00000000

Code for Version 1:
D3000000 00000000
00379EB4 00000000
00379EB8 00000000
D2000000 00000000

Code for Version 1.4:
D3000000 00000000
0037A140 00000000
0037A144 00000000
D2000000 00000000

004E2D10 40A49249
004E3310 41100000
004E341C 40249249
004E3420 3EA49236
58084760 03A05007
080845E8 13A05003
080845EC 03A05002
0808475C 13A05005
08084760 03A05003
D0000000 00000000

Only works on Version 1.4

DD000000 00000200
481FB58C 08200000
481FB92C 08200000
B81FB58C 00000000
C0000000 00000002
DA000000 0000000E
D7000000 00000010
D3000000 00000000
B81FB92C 00000000
D1000000 00000000
D3000000 00000000
B81FB590 00000000
C0000000 00000002
DA000000 0000000E
D7000000 00000010
D3000000 00000000
B81FB930 00000000
D1000000 00000000
D3000000 00000000
B81FB594 00000000
C0000000 00000002
DA000000 0000000E
D7000000 00000010
D3000000 00000000
B81FB934 00000000
D1000000 00000000
D3000000 00000000
B81FB598 00000000
C0000000 00000002
DA000000 0000000E
D7000000 00000010
D3000000 00000000
B81FB938 00000000
D1000000 00000000
D3000000 00000000
B81FB59C 00000000
C0000000 00000002
DA000000 0000000E
D7000000 00000010
D3000000 00000000
B81FB93C 00000000
D1000000 00000000
D3000000 00000000
B81FB5A0 00000000
C0000000 00000002
DA000000 0000000E
D7000000 00000010
D3000000 00000000
B81FB940 00000000
D1000000 00000000
D3000000 00000000
D2000000 00000000

Then press L.