Enduring Bondwarden’s last ability puts counters that were on the creature with the ability onto the target creature, not just its +1/+1 counters.

If a backup ability causes another creature to gain abilities, the creature with backup will still have those abilities.

Backup confers only abilities that are actually printed below it. Any abilities that are gained by the permanent are ignored, including abilities gained due to a resolving spell or ability or copy effects.

The abilities that backup grants to the target creature are determined only once, at the time the ability triggers. They won’t change if the permanent with backup loses any abilities before the backup ability resolves.

If a permanent enters the battlefield as a copy of a card with a backup ability or a token is created that is a copy of that card, the order of the printed abilities is maintained.

In some unusual cases, you may end up putting the appropriate counters on more than one permanent. For example, if you control The Ozolith when Enduring Bondwarden dies, you’ll put the appropriate number of each kind of counter onto both The Ozolith and the target creature.

Enduring Bondwarden’s last ability doesn’t cause you to move counters from the creature with the ability onto the target creature. Rather, you put the same number of each kind of counter the first creature had when it died onto the target creature.

If a backup ability targets the creature with backup, that creature will get +1/+1 counters, but it won’t gain additional abilities.

If the creature with Enduring Bondwarden’s last ability has -1/-1 counters on it when it dies, that ability will include those as well. This may result in the recipient also dying.