I have 3 questions: 1)how do you get joyus tower and if you know, can..

1. Ok the all you have to do to get Joyous tower is to recruit latias and latios get the friend area sky blue plains then the next day you will see ekans and medicham by wiscashes pond.You go up to them and they speak about a cave.Then you go and do a normal mission and repeat the process untill the only person there is ekans.When this is done go to the pelipper post office and look on the bulletin board and there will be a rescue for medicham in wish cave.
This also unlocks Wish cave.(im not exactly sure what you mean on the last part of the question.)

2. As groudons recruitment is -10% and he is **** in size I would suggest you bring a level 100 Pokemon with a friend bow to bring his recruitment rate up to 24.9%

3. Well being a high level water Pokemon in fiery field I don't see why you find it hard but the advice I can give you is.

Bring a tight belt.(Stops you from being hungry)
Bring a few reviver seeds.(Revives you)
Bring all your strongest pokemon.(Helps you to floor thirty)

When I go to some dungeons I bring a ghost Pokemon with a tight belt so I never get hungry when I go through the walls.

Hey I'm pretty sure you need to get the friend area SKY BLUE PLAINS and for the 2nd part of the question I don't no what your talking about.For your second question I suggest you bring a maximum body size to the save point AND a FRIEND BOW (MT.FARAWAY floor 30) which will boost his recruitment percentage from -10% to 0%. I did this with a level 55 charzard and only had to challenge him 3 times to catch him. For FIERY FIELD make sure you DO NOT bring a FRIEND BOW,also bring your 3 most powerful ROCK,GROUND,WATER and DRAGON type Pokemon you can hold.Then on the 29th floor ditch eveyone but max your PP out and get ready to fight.

PS:Groudon has a body size of **** and Entei can NOT be recruited the first time you beat him and his recruitment percanetage is 0.01.

To get joyous tower you have to get the friend area sky blue plains from an optional mission and clear pitfall valley.

The easiest way to recruit groudon is probsbly to have a level 100 Pokemon with the friend bow to have a really good recruitment rate

Try levelling up a little more, bring lots of reviver seeds
Here are some wonder mail for joy seeds
I was KO'd...
This dungeon is scary!
I feel faint... Please help...
Client: Camerupt
Objective: Help me.
Place: Mt. Steel 1F
Difficulty: E
Reward: Joy Seed + ? + ?
4?FF X?+? ?7?6
!R?K F466 R9??

I'm in trouble...
I can't move another step.
...Gasp! Waaaaaaaah!
Client: Camerupt
Objective: Help me.
Place: Mt. Steel 2F
Difficulty: E
Reward: Joy Seed + ? + ?
F?FF X?F? ?766
QR?K F?66 R0??

I'm too tired to move.
This dungeon is scary!
Where am I? Help!
Client: Camerupt
Objective: Help me.
Place: Mt. Steel 3F
Difficulty: E
Reward: Joy Seed + ? + ?
1?FF X?0? ?76?
SR?K F466 R4??

I can't get home!
I lost in a battle...
Help!
Client: Camerupt
Objective: Help me.
Place: Mt. Steel 4F
Difficulty: E
Reward: Joy Seed + ? + ?
1?FF X?(...)? ?77?
YR?K F?66 R5??

I'm scared!
Fighting a tough foe was a mistake...
Rescue is requested!
Client: Camerupt
Objective: Help me.
Place: Mt. Steel 5F
Difficulty: E
Reward: Joy Seed + ? + ?
1?FF X?Y? ?776
JR?K F466 RH??

I'm in trouble...
This dungeon is scary!
Rescue is requested!
Client: Camerupt
Objective: Help me.
Place: Mt. Steel 6F
Difficulty: E
Reward: Joy Seed + ? + ?
4?FF X?T? ?7N6
JR?K F?66 RH??

I'm in trouble...
I was done in...
Someone!
Client: Camerupt
Objective: Help me.
Place: Mt. Steel 7F
Difficulty: E
Reward: Joy Seed + ? + ?
4?FF X?X? ?7N6
KR?K F466 RR??

I can't get home!
I've reached my limit...
I feel faint... Please help...
Client: Camerupt
Objective: Help me.
Place: Mt. Steel 8F
Difficulty: E
Reward: Joy Seed + ? + ?
1?FF X?X? ?7P6
+R?K F?66 R(m)??