To swap robots:
Edit the file(s) fightr#.af and change the first byte to the desired
robot (ex: jaguar=0, nova=10), change the first 00 of the jag file to
0A and the nova to 00 (0A goes in the selected file, understand?) then
rename the files.

Sound Effects Test:
Press/hold ALT-S-F on title screen to activate a new menu item in
the configuration menu (Sound Effects Test).  Hehehehe.

Choosing Hidden Difficulty levels
To choose Deadly Level (for ONE PLAYER only), keep pressing the right arrow
key even though it is on Champion Level already. Deadly will show up after
about 5-8 kep presses.

To choose Ultimate level (for ONE PLAYER only), press and hold down these
keys: O+M+F. Press them together at once will let you choose Ultimate level.

If you are in Deadly Level and (may not be needed) in Hyper Mode,
doing a Destruction on certain boards will result in slightly modified
forms of the Destruction being done. To try this out, choose Jaguar
and fight in ONE PLAYER mode with Deadly Hyper on, and do a destruction
to opponent on the FIRE stage (the one with the 'grill' <-- BIG HINT on
the floor with the flying fireballs). Watch linoleum fly!

*=(Hidden "Unranked Challengers" on a hard level)=*
Unranked Challengers pop up if you do a destruction on someone:

Christian - Crystal's brother (when you defeat Crystal with destruction)
Jazz Jackrabbit - D'uh (defeat #2 rank)
Eva Earlong - Jazz's Girl (in World Championship)
Devan Shell - Arch Foe of Jazz Jackrabbit (W.C.)
Bethany - Girl who says "Don't hurt me" while she kicks yer butt (W.C.)
Angel - The "moontian" (W.C.)
Iceman - Shows up when you beat a female (Or #1 in NorthAm). Defeat Iceman
         with Shadow to get the Ice Floor Freeze in Tournament mode!
Nicoli - Mysterious person who fights you when you beat #1 in W.C.
FIRE - In Fireball Stage, Do a destruction (Only in one player, not two
       then keep repeating the destruction (Only known to work by using
       Jaguar, Electra, and Shadow, so send me the rest!)
       If you defeat FIRE using Katana, you will get a new move for Katana:
       FIREBALL (as done by Fire himself): D,B+P
ICE - in Ultimate difficulty only. After defeating Fire, do a destruction
      on him and then keep repeating the move for the destruction.
      If you defeat ICE using Shadow, you will get a new move for Shadow:
      ICE FREEZE (as don by ICE _and_ Iceman): F,D,B+P
Steel Claw - Cyborg from Hell (I think he's an Iron Fist member)
    *** Beat Steel Claw and get a Special Item!  ***
    *** For Jaguar, it's two cannons in one shot ***
    *** Other robots get some other enhancements ***
        *** Note: Some other HUD's can give you the  ***
        *** enhancements instead of Steel Claw. :)   ***
        *** Having gotten more than one enhancement  ***
        *** will make your 'bot a _LOT_ better (hint)***

To change the colors of the 'bots in 2-player or 1-player:
use your keyboard in the 'bot selection phase, hit the 1,2 and 3 key for
'bot one's color (not keypad) and the 4,5 and 6 key to change the color of
the second 'bot.
                                                                   
Some stuff to type while playing:

In any menu except the gameplay menu, press and hold 2097 for 2 sec.
Then go to Gameplay menu and you'll have access to an advanced options
menu.

While playing, press and hold  BIG  and any number from 1-9 to increase
or decrease amound of scrap falling off a robot when hit.

While playing, press and hold  REIN  for 2 seconds to get a lot of 
scrap falling from the top of the screen.

** Please note ** In all the editing below there appears to be
differences in the registered and unregistered versions
As always back up your files before editing them!

Using debug, enter: debug [savegame.chr]
at the - prompt, enter:

E 128 FF FF FF     (for the big money cheat)

E 11C C1 E8 C3 EA
E 204 34 71 A2     (for max MECH power, speed, armor, stun res)
E 210 54 30 AC
E 214 64 50 D0

E 120 D4 C1 D6     (for max PILOT power, agility, endurance

E 11B C4           (to use PYRO)
E 11B C5           (to use THORN)
E 11B C6           (to use SHADOW)
E 11B C7           (to use JAGUAR)

To exit debug and save your changes enter:
W
Q

Wait, here's another one.

Hi there. Well, ive been busy with my hex editor tonight, 
and I have found which offset in a .CHR file that the robot 
type is stored in.  Anyways, with any hex editor, go to offset 
$1B, and below input any byte number, e.g if it's C7(Jaguar) 
change it to CD and you get a Nova. Here's all the robot's below

C0=Flail
C1=Shredder
C2=Katana
C3=Electra
C4=Pyros
C5=Thorn
C6=Shadow
C7=Jaguar(default robot when you start a new tournament)
CD=Nova
CE=Chronos
CF=Gargoyle

And even more!

Bytes 33, 34, and 35 affect your agility, power, and endurance 
(I believe in that order, although I'm not sure).  While the 
highest level possible for each of these attributes within the 
game is 25, you can actually set it far above the "maximum".  
Try setting byte 33 to AF, byte 34 to B0, and byte 35 to B1.  
I believe these are the absolute maximums.  Now your character 
will be a virtual god, being able to jump off the screen (do a 
spring jump for the best effect!), inflict up to 192 points of 
damage, and more.

Bytes 41, 42, 43 and 44 control the money.  Set them all to A0 
for 2 BILLION DOLLARS!!!

Bytes 45, 46, and 47 control the robot colors.  (Try this combo, 
it's my favorite: D1, D0, D3)

You've already covered byte 28...

Bytes 29, 30, 31, and 32 control the robot abilities (arm speed, 
leg speed, etc).  They can be set above the normal maximum, BUT 
the game always seems to mess up, and you mystically end up 
millions of dollars in debt.  If you really want max abilities, 
I would just use the money trick and buy the stuff you want.  
Much simpler.  Here are some of the "normal" maximums, though:

Jaguar 0D D1 62 EB
Pyros  40 D1 CC D2
Thorn  C1 D8 2F EB
Shadow 0D E9 23 D3

(Can you tell I don't have the registered version yet?)

Byte 27 controls the rank, which you can do some pretty neat 
things with.  I have the shareware version, so I don't know 
how this will apply to the full version, but I'll post it 
anyway.  In the North American tourney, you start in 11th 
place.  If you set your rank BELOW this, go into the tournament 
and go to the arena, you will find a secret character there!  
You can enter the arena over and over again, win or lose, to 
fight the same secret character.  Don't forget to remember your
old rank so you can set it back when you're done!  Here are the 
values and the corresponding special characters:

Iceman     CA (Rank 12)     Some other values: C7 (Rank 1)
Jazzy      CB (Rank 13)                        C4 (Rank 2)
Christian  C8 (Rank 14)                        CD (Rank 11)
Steel Claw C9 (Rank 15)

--- another one ---

debug filename.chr
-e128 A0 A0 A0 A0
-w
-q

This gives you over two billion dollars!