When you complete the indicated number of Multiplayer matches the corresponding bonus becomes unlocked in multiplayer mode:

Unlock Special Items On/Off Option:
Complete 5 Multiplayer matches.

Unlock Missile Launcher:
Complete 5 Multiplayer matches.

Unlock Missile Launcher Only mode:
Complete 10 Multiplayer matches.

Play as Peppy Hare:
Complete 15 Multiplayer matches.

Unlock Gattling Guns:
Complete 20 Multiplayer matches.

Unlock Crown Capture Mode:
Complete 30 Multiplayer matches.

Unlock Titania Desert Map:
Complete 40 Multiplayer matches.

Unlock Sure Shot Scuffle Mode:
Complete 50 Multiplayer matches.

Unlock Simple Map 4:
Complete 60 Multiplayer matches.

Unlock Fireburst Canon:
Complete 75 Multiplayer matches.

Unlock Booster Packs:
Complete 90 Multiplayer matches.

Unlock Booster Pack Bout:
Complete 110 Multiplayer matches.

Unlock Zoness Sea Base Map:
Complete 130 Multiplayer matches.

Unlock Star Wolf Team's Wolfen Ship:
Complete 150 Multiplayer matches.

Unlock Predator Rockets:
Complete 170 Multiplayer matches.

Unlock Cluster Bombs:
Complete 200 Multiplayer matches.

Unlock Booster Packs and Launcher Tilt:
Complete 230 Multiplayer matches.

Unlock Simple Map 5:
Complete 260 Multiplayer matches.

Unlock Survivor Mode:
Complete Story mode.

Unlock Xevious Mini-Game:
Complete Story mode with ALL Silver friendship medals.

Unlock Demon Sniper Rifle in Multiplayer Mode:
Collect ALL of the flags on any level to get this rifle which is able to destroy Master Tanks or Arwings with just one shot.

Unlock Wolf O'Donnell in Multiplayer Mode:
Either collect the friendship medals on ALL 10 levels or complete Story mode with no allies killed.

Unlock Peppy Hare in Multiplayer Mode:
Complete 15 versus mode matches.

Unlock Xevious Bonus Game:
Get every silver medal in Story mode

Xevious:
Collect all Silver medals in Story mode

Wolf:
Beat the game on Bronze difficulty

Peppy Hare:
Earn a Bronze medal on all 10 of the game's missions:

Rocket Launcher in Multiplayer Mode:
Play 5 multiplayer matches

Missile Launcher Only Mode:
Play 10 multiplayer matches

Peppy Hare as Playable:
Play 15 matches

Gattling Guns:
Play 20 multiplayer matches

Crown Capture Mode:
Play 30 multiplayer matches

Stage: Titania Desert:
Play 40 multiplayer matches

Sure-Shot Scuffle Mode (1-hit kills):
Play 50 multiplayer matches

Simple Map 4:
Play 60 multiplayer matches

Fireburst Pods:
Play 75 multiplayer matches

Booster Packs:
Play 90 multiplayer matches

Booster Packs Brawl Mode:
Play 110 multiplayer matches

Stage: Zoness Sea Base:
Play 130 multiplayer matches

Wolfen:
Play 150 multiplayer matches

Predator Rockets:
Play 170 multiplayer matches

Cluster Bombs:
Play 200 multiplayer matches

Booster Pack and Launcher Tilt Mode:
Play 230 multiplayer matches

Stage: Simple Map 5:
Play 260 multiplayer matches

Survivor mode for Single player:
Complete the game once

Demon Snipers VS mode:
Collect all 50 flags in Single player mode

Unlock Wolf O'Donnell for Vs. Mode
Beat all 10 missions without any of the other Star Fox Team members retiring

during those missions.


Multiplayer Stages

Katina Outpost Complete Katina:
Complete Frontier Base Battle once

Fichina:
Complete 'Fichina: Into the Storm' once

Planet Sauria:
Complete 'Sauria: Reunion' once

Corneria City:
Complete 'Corneria: War Comes Home' once

Space Station:
Complete 'Orbital Gate: Incoming' once

Aparoid City:
Complete 'Aparoid Homeworld: Breaching the Defenses' once

Inner Sargasso Hideout:
Complete 'Sargasso Space Zone: Hostilities Revisited' once

Outer Sargasso Hideout:
Complete 'Sargasso Space Zone: Hostilities Revisited' once