I sure have and good god, this game is hard. I especially hate the Roller Coaster stage. It's where you drive around this roller coaster track to the finish line but to make matters worse, there's a biker rat on your tail and if he touches you, you're dead. You only have a few tries and with only little continues, it makes Battletoads one of the most frustrating video games ever.

No, the Gamestop didn't have it :(

Yes i have.

I've played Battletoads & Double Dragon: The Ultimate Team.

I remember having it at a local videoshop here in Australia. It was an imported title so you needed to rent a converter from them in order to play it. Using the converter you needed to put the imported game in one slot, a local game in the other and then slot it into the system. It was pretty janky. Don't remember much about the game though, don't think I enjoyed it at  all.

One of my favorite games as a kid.

Played it to death as a kid and have loads of nostalgia for it. But I don´t think that makes it a very good game tho. As stated, very frustrating.

I liked the quirky theme and characters but found it too hard and frustrating

Yes; I remember almost nothing, since the whole game pretty much blurs together, but I know that, since that was the only game I owned for a while, me and my cousins beat it so many damn times. 
 
Fond memories, but I don't want to go back to it, since I'm not sure I could put up with the difficulty at this point.

" I've played Battletoads & Double Dragon: The Ultimate Team. "

Yeah man, I just played this for the first time today with my friend. We got to the hoverbikes stage over time and never once beat it