main is riolu partner is vulpix
riolu has quick attack, bite, force palm, and brick break
vulpix has flame thrower, ember, imprison, and fire spin
and the sunflora episode is just annoying with three haunter at once, i can kill 1 but then the other 2 kill me or loudred
Ahh... is it you and your Partner that get KO'd, or is it Shaymin? (Keep in mind that Shaymin is Grass-type and the Grimer/Muk are Poison, so poor Shaymin has a type disadvantage.)
Have you considered Dig on your Riolu, if only momentarily? That will allow you to dodge attacks and do x2 damage to Grimer and Muk. Otherwise, you'll want to attack with moves that give you STAB.
You could level Vulpix up to 44 so that she learns Extrasensory, which is a nice Psychic-type attack (thus deal x2 damage to the Grimer). Imprison is nice because you can stall your enemies that way.
Remember that you can switch your Partner's moves on and off in order to assure she uses the attack you want her to.
Since you can't use Orbs in Boss Battles, Seeds are your next best bet. Here are some suggestions I have:
Reviver Seeds, of course, for unexpected KOs. (They're nice for Shaymin too.) Also, Oran Berries to heal your Team--you'll want to keep a close eye on everyone's health.
Quick Seeds will boost your Speed level (when you eat them) so that you can attack multiple times in one turn, which is always handy. Violent Seeds that will maximize the Attack of the Pokemon who eats it. If you want to score 1KHOs, this is probably the way to go, along with STAB attacks, or those that are super-effective against Grimer. Blinker Seeds/X-Eye Seeds/Sleep Seeds/etc. to stall your opponents. There are a lot of Grimer, so being able to shut some of them down while you take out the rest is handy. Of course, Vulpix already has Imprison, but it can only be used when she is adjacent to the enemy--Seeds can be thrown in a straight line, thus you don't have to risk taking an attack.
When I fought this battle, I blocked Shaymin off from the Grimer so that there was no chance it'd be hurt. Shaymin doesn't have that much HP. And Breloom, Machoke, and Mawhile help you in this fight, right? Be sure to use their aid to your advantage.
If you also are willing to retreat from the mountain and head back to Treasure Town, you can recruit a Pokemon that learns a move that affects the whole room (ex: Discharge, Heat Wave, Silver Wind, Ominous Wind, etc.) Being able to attack every single Grimer/Muk in one turn is very, very nice. It will also help you with future Monster Houses.
As for the Sunflora episode, you have the move Bullet Seed, right? The Haunter line for you, so you should throw Sleep Seeds (or Grasswhistle) to keep them still, then come up to either the right or left side of the line. Then Bullet Seed them all to death. Loudred has Astonish, which is nice, because it's super-effective against them. My main strategy was just to keep them all asleep with Grasswhistle while Loudred hammered away at their HP. Then I used Bullet Seed and finished them off.
