If you mean PP by HP, it is not possible. But, if it is PP, remember that Struggle has no PP and just lasts infinitely. Since you just want to know about triple recoil, it is possible.
Because Ferrothorn is the only Pokemon with the ability Iron Barbs, the only possibility is to use Ferrothorn.
You would first need to make the opponent use Struggle without losing HP. But the next step is the problem. This is a citation from Smogon Forums:
...using Leppa Berry with Heal Pulse, Recycle, a healing move (such as Slack Off or Soft-Boiled) and Block/Mean Look/Spider Web. Fortunately only Slowpoke, Slowbro, Slowking, Blissey and Smeargle are legally able to use this combination (Ralts, Kirlia, Gardevoir and Gallade as well if you count Wish). To use the strategy, one of these will switch into a defensive Pokemon, or one unable to 2hko them, use Block and then PP stall the opponent with recovery and Leppa Berry + Recycle. Once the opponent begins to Struggle, the user can simply continue to Heal Pulse, with Leppa Berry + Recycle, until the opponent forfeits.
Ferrothorn cannot use the Leppa Berry + Recycle because it cannot learn Recycle.
Making the other Pokemon never run out of health is only available through creating an endless battle, as shown by the information above.
Therefore, you cannot make the Pokemon use Struggle without it losing HP.
If you actually meant PP, it is important to note that Struggle does not have any PP.
Since, you just want triple recoil, it is actually legit if you can stall it long enough. Once it no longer has PP, it will use Struggle. It's important to note that this isn't really an effective strategy, however. (especially when the Pokemon is using contact moves; it'll faint too quickly from the Iron Barbs and the Rocky Helmet)
Hope this helped!
But I'm really confused about
Struggle without having the other Pokemon run out of PP.
Source: Smogon Forum, Pokemon Database: Move Recycle, Experience
