While loop going infinitely because of a class method that returns wrong values - Python

I'm just playing around with python concepts such as while loops, classes, methods and return values. The thing is, to make it "more attractive" I'm doing it with a class that's named Pokemon().

The code looks like this:

import random

class Pokemon():
    def __init__(self): #Pokemon attributes
        self.health = 100
        self.damage = 5
        self.__lives = 3 #? //Not used
    
    def checkalive(self, opponent): #Check if the pokemon's still alive, args: the pokemon and the opponent
        while self.health and opponent.health > 0: 
            return True #If both of them alive, return true
            break
        
        return False #If neither of them  alive, return false

    def attack(self, opponent): #Attack function, args: the pokemon and the opponent
        
        while True:
            check = self.checkalive(opponent) #Check if the pokemons are alive
            while check == True: #In case it returns True go on with the combat
                randomNumber = random.randint(0,5) #Just creating a random number
                if randomNumber == 3: #If that random number equals to 3 (20%) the opponent will defend itself and will counterattack our Pokemon
                    self.health -= opponent.damage
                    print("Got it wrong! You've got " + str(self.health)  + " HP remaining.")
                    
                else: #If not (80%), just go on with the combat
                    opponent.health -= self.damage
                    print("The opponent now has " + str(opponent.health) + " HP! Your pokemon still has got " + str(self.health) + " HP left.")
                    
            
            print("End of combat") #Once one of them is dead, end of combat
            break


Squirtle = Pokemon() #Our pokemon
Pikachu = Pokemon() #Opponent
Squirtle.attack(Pikachu)

I've created two very basic methods. One is checkalive(), just as its name says it just makes sure if the Pokemons involved in a combat are still alive, returning True or False values.

The other one is attack(), that basically just hurts the Ally Pokemon/Opponent Pokemon depending on a probability of 80%/20%. It is a really simple code and before implementing the checkalive() function it worked perfectly. However, now the while runs an indeterminately amount of times, going below negative health values. I tried to figure what's going on, tried to change the "While" for an "If" condition statement and etc, but still no clue. Any suggestion would be really appreciated.

You are forgetting to update the loop condition! Notice that check is never updated in your while loop. What you have to do is the following:

while check == True:
    ... # do whatever you would like to do like generate random number etc.
    check = self.checkalive(opponent)

This should work.