^^^

Not to mention, you only get FIVE Hearts for TWO People!

EDIT: I'm gonna Go back to SSE to practice on Tabuu, as it's hard to make it to him And I get KO'd within the first 2 minutes every time. 

My roommate and I just beat Boss Battle mode on Very Hard using none of the hearts. We used 2 Charizards and spammed rock smash (forward B) for most of the bosses. Its extremely effective. Tabuu you either need to beat down before he does his 3 rings of death, or get on the ground and side step all three bursts.

 In 15 minute... I don't remebeer who I was... I'll look it up later... I was either Kirby or Sonic... Anyway, I avoided as much damage as possible, but as soon as I saw a FAN, I grabbed it and used it on a CPU (near one of the edges) and they all joined in. I just kept button mashing the A button (pausing at some points). I kept using it for about 6 min in the beginning, then it dissapeared, then I used another one for the rest of the match (It spawnedabout a min. later) I actually got a lot of kills too.

Beating Boss Mode with all characters actually goes fairly quickly, as you can do it on easy. It only took me around an hour and a half (fastest time was 1:30 with Fox, Woot!). All-star mode, I am going to use a hammer on.

I'm getting really Frustrated.

I"ve gotten to Tabuu with DK, only to get annihilated within 2 minutes

As Pokemon Trainer (I Use Charizard AND Ivysaur) I've gotten to my 2nd-to last person (one before Tabuu) wich happend to be Rayquaza, who all the sudden got amazingly steroid-powered crazy pattern-changing skills I'm about to say F*** it and just use my first hammer.

To my knowlege the golden hammers don't work on that challenge.  Why Nintendo choose to make certain ones unopenable with a golden hammer it beyond me, but that's the way it is.  You just going to have to do it the  hard way

Our only hope is that is somehow if you obtain all the other challenges and that is the only one left, then at that point perhaps it lets you use the golden hammer.

In the mean time L.C.E.C. you should practice one of gamings well known tactics.  Put it away (try some other game or different challenges) and come back to it some time later.  (A couple of days? a week? two weeks?)  That has worked for me many times.

You can't use a Golden Hammer on "Clear Boss Battles on Intense difficulty." It really sucks.

Finally finished Boss on intense. Only took me about 10 or so tries and I had it today. Like Fagarcia75 said, you sometimes do better when you step away for a bit. When I was playing yesterday(after many hours of trying) I was having a hard time making it to Tabuu. Today I made it on my first or second try with Lucas, after experimenting with Pokemon Trainer a bit. First time I made it to him, had him to about 25% health and screwed of the red rings of death dodge. Second time I made it to him I was one good hit away. Third time I finished him rather quickly, with about 50% damage taken. Things just felt different today when I first started playing; I was having almost zero problems with all of the bosses leading up to the final showdown.

I went back and tried Boss on very hard, just to see if it would be a good way to farm coins. On very hard it seemed like all the bosses were slow as molasses. They were so slow it was messing with my timing badly. Still, I was only hit twice on the way to Tabuu, entering the fight with 14% damage. I finished him with (I think) 34% total damage taken. It's crazy how just a week or so ago I was struggling on very hard, and now it's a cakewalk.

beat boss battle on  very hard with charizard last night. I got to the end boss on intense and was doing quite well, but I have a hard time dodging that attack that looks like a butterfly flying across the screen. If it grabs you it thows you down and you go flying away.

 If you're playing as Charizard just use Pokemon Change to avoid that attack, makes you untouchable for a brief time. It's a pain to Rock Smash Tabuu anyways, and you can change back during other attacks. I actually kind of perfer Squirtle on Tabuu since he moves a lot faster.