The first set of codes here is for the US release of Spyro: AOTR and are used
with a GameShark (V3 or 4)
[M] Must Be On 987BBAD37225 F706A7111F8C E62E4E6ACA0C
Have 9000/9000 Total Gems E406A3FB55D1
Have 12/12 Total Hearts EA776D791DD9
All Items Collected 5DB9F9488F47 A8418C3917C9
Access all Lands 648F7927EF32
Dragon Shores: Have 900/900 Gems 0E39471534BA
Fairy Library: Have 500/500 Gems A0C75213558A
Yeti Serengeti: Have 550/550 Gems 550E43D672E5
Byrd Barracks: Have 600/600 Gems E8D036EB4551
Thieve's Guild: Have 600/600 Gems BBF036D011D5
Rabbit Habitat: Have 600/600 Gems F9D036D251D5
Banana Savannah: Have 600/600 Gems AAF036D115D1
Kangaroo Hoodoos: Have 700/700 Gems 71CF6256708E
Moneybag's Mansion: Have 800/800 Gems 9F30039011F5
Cheetah Spot Spa: Have 650/650 Gems 97272768032E
Rhynoc's Clocks: Have 800/800 Gems 8E30039115F1
Chateau Ripto: Have 900/900 Gems D507471251AE

These next codes are for the European release of the game and are similarly for
use with a GameShark.

[M] Must Be On 911EA638C432 ABEC5502DF82 0058D6F528D4
Have 9000/9000 Total Gems 763C069B2017
Have 12/12 Total Hearts 47901EE32454
All Items Collected 55C3EFA067AB 67F41627F6D6
Access all Lands 9A4563700537
Dragon Shores: Have 900/900 Gems 9BA04A6FCA6C
Fairy Library: Have 500/500 Gems 0235327FB0FF
Yeti Serengeti: Have 550/550 Gems DC6EC0DF088B
Byrd Barracks: Have 600/600 Gems 66BD3FDA7316
Thieve's Guild: Have 600/600 Gems 65BBB8CBF218
Rabbit Habitat: Have 600/600 Gems 64BFB8DB721A
Banana Savannah: Have 600/600 Gems 67B93ACBF21C
Kangaroo Hoodoos: Have 700/700 Gems 8827D0FB38FB
Moneybag's Mansion: Have 800/800 Gems 75BA884FC209
Cheetah Spot Spa: Have 650/650 Gems 317285EA81E0
Rhynoc's Clocks: Have 800/800 Gems 77B80A4FC20D
Chateau Ripto: Have 900/900 Gems 1036807F00EA

And here are some CodeBreaker codes too, these are for the US version:

1E Enable Code (Must Be On) 0000BFBA 000A
10001342 0007
1 Infinite Jewels 8300301C 0384
2 Have All Jewels Game Total 8300301E 2328
3 Have All Hearts Found 33003029 000C
4 Have Everything Unlocked 43002FE6 FFFF
00000007 0002
5 Have All Levels Open 83003000 FFFF
6 Time Always 00:00:00 43002922 0000
00000004 0002
7 Press Select To Escape Any Level 74000130 03FB
32039E94 0005
Have All Jewels Found Codes
8 Dragon Shores 73002950 0000
83002950 0384
9 Fairy Library 73002952 0000
83002952 01F4
10 Yeti Serengeti 73002954 0000
83002954 0226
11 Byrd Barracks 73002956 0000
83002956 0258
12 Thieve's Guild 73002958 0000
83002958 0258
13 Rabbit Habitat 7300295A 0000
8300295A 0258
14 Banana Savannah 7300295C 0000
8300295C 0258
15 Kangaroo Hoodoos 7300295E 0000
8300295E 02BC
16 Money Bag's Mansion 73002960 0000
83002960 0320
17 Chetah Spot Spa 73002962 0000
83002962 028A
18 Professor's Secret Lab 73002964 0000
83002964 0320
19 Rhynoc's And Clocks 73002966 0000
83002966 0320
20 Chateau Ripto 73002968 0000
83002968 0384