You only need one medicine bottle. For the big lava pits, just bounce on as many enemies as possible with Bop, then take a hit on the last one. Then use the short invincibility time to walk on the bottom of the lava with Gil. You can make it pretty nicely without taking any more damage. You do not need Shades or Freeon-leeon or any secret weapons.
I wonder if manipulating enemies into dropping energy balls would be faster than grabbing the medicine...
Here's the current route as I envision it:
Start
Get Freeon-Leeon
Cross ice-area (use Freeon-Leeon)
Cross gap without Shades, move up
Tree area (get egg and return it to bird)
Go back and up, across clouds, defeat boss and get suction cup
Go down
Enter gate room from Ice Cave
{get medicine if it's faster than manipulating enemies along the way}
Get Gil and Red Key
Choose the faster path of these two (test both):
1. Go down, to starting area, right and dive into the water (the first body of water encountered in the game) , go right at the first intersection, then right again, through pipe, then up twice. You'll come up in a lake to the left of the tree area. OR instead of coming up in that lake, go right at the last intersection and come up on the tree area lake instead.
2. Go back to the throne room, go through it, climb up ice wall, go right, climb up, then go right again (you'll encounter the lake to the left of the tree area)
Go through tree area (faster than the previous time because of suction cup),
Take a ride with the bird,
climb up a wall, go right, enter cave
activate water faucet, enter newly accessable water tunnel
Go through extremely long water maze with Gil
Kill boss and get Gil's seret weapon.
Go back
From tree area lake, choose the faster path from these two (test both):
1. Go left and up, come up in lake to the left of tree area. Then go left again and down megashaft. Now go right from the botton and bomb the wall with Gil's secret weapon.
2. Go left and then down, right, through megashaft pipe, down and left. Get out of the water in the mines, leave the mines to the right (where you normally first enter them). Now go right and bomb the wall with Gil's secret weapon.
Cross the lava pits using the strategy I mentioned earlier, kill armor guy, get Blue key.
Head back and go up megashaft.
Enter gate room from the Ice Cave, go through.
Bomb through 999 walls with Gil's secret weapon, get Green key.
Go back to the gate room, kill boss
By the way, there's a great map for the game here:
http://www.vgmaps.com/Atlas/NES/Ufouria-TheSaga-Ufouria.png
It's very easy to plan the route if you have this map. :D
Edit: Bleh! Of course, you can just use Gil to charge Bop, so you can skip Bop-louie's secret weapon.
Edit: actually, forget that whole route. It could be faster to get Bop-louie's secret weapon after all, so you can enter the water maze from the opposite direction.